JP7312005B2 - Polyester resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyester-based resin composition having excellent hydrolysis resistance.

Polyester-based resins are generally excellent in transparency, mechanical strength, workability, solvent resistance, recyclability, etc., so they are widely used for fibers, films, sheets, etc. It is also used for device housings.
However, polyester-based resins are prone to hydrolysis and deterioration over time, so a carbodiimide compound is sometimes added for the purpose of suppressing this and improving hydrolysis resistance.

It is also known that the hydrolysis resistance can be further improved by using an epoxy compound together with the addition of the carbodiimide compound.
For example, Patent Document 1 describes adding an epoxy compound and a carbodiimide compound to an aromatic polyester for the purpose of improving hydrolysis resistance.

JP-A-1-174557

Specifically, the above Patent Document 1 discloses a monocarbodiimide compound in which a hydrocarbon group is bonded to both ends of a carbodiimide group, or a polycarbodiimide compound having a hydrocarbon group directly bonded to a carbodiimide group at both ends. ing. Such a carbodiimide compound tends to generate isocyanate gas due to decomposition of the carbodiimide compound by heating during melt kneading or molding of the polyester resin composition, and is not preferable from the viewpoint of the working environment in the production of polyester resins. there were.

In addition, aliphatic carbodiimide tends to generate isocyanate gas as described above, and even when used in combination with an epoxy compound, the effect of improving the hydrolysis resistance of polyester resin is sufficient. It was indescribable.

The present invention has been made to solve such problems, and it is possible to obtain a polyester resin having excellent hydrolysis resistance, and to generate isocyanate gas by heating during melt kneading and molding processing. An object of the present invention is to provide a polyester-based resin composition in which is suppressed.

The present invention uses a predetermined carbodiimide compound and a compound having an epoxy group and/or a hydroxyl group in combination to impart better hydrolysis resistance to a polyester resin than before, and This is based on the discovery that it is possible to obtain a polyester-based resin composition in which generation of isocyanate gas due to heating during kneading or molding is suppressed.

That is, the present invention provides the following [1] to [7].
[1] A polyester resin (A), a carbodiimide compound (B) represented by the following formula (1), and an organic compound (C) having at least one of an epoxy group and a hydroxyl group, wherein the carbodiimide compound ( The content of B) is 0.1 to 10.0 parts by mass with respect to a total of 100 parts by mass of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C), and the carbodiimide A polyester-based resin composition, wherein the mass ratio of the organic compound (C) to the compound (B) is 0.1 to 10.0.

(In the formula, R ¹ and R ² are each independently a residue obtained by removing the functional group from the organic compound (Y) having one functional group reactive with an isocyanate group.
R ³ is a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. The diisocyanate compound has a benzene-based aromatic ring directly bonded to the isocyanate group, and does not have a substituent at both ortho-positions of the benzene-based aromatic ring to the isocyanate group. A plurality of R ³ are the same or different from each other.
R ⁴ is a divalent residue obtained by removing two hydroxyl groups from a diol compound. When there are multiple R ⁴ s, each R ⁴ is the same or different.
The organic compound (Y) is one or more selected from monoalcohols, monoamines, monocarboxylic acids and acid anhydrides.
X ¹ and X ² are each independently a bond formed by reaction between the functional group of the organic compound (Y) and the isocyanate group of the diisocyanate compound.
m is a number from 0 to 50, and n is a number from 1 to 50. )

[2] The organic compound (C) is one or more selected from an epoxy compound having an epoxy equivalent of 170 to 750 and a hydroxy compound having a hydroxyl group equivalent of 170 to 750. The polyester according to [1] above. system resin composition.
[3] The polyester-based resin composition according to [1] or [2] above, wherein the organic compound (C) is solid at 25° C. and 1 atm.
[4] The polyester according to any one of [1] to [3] above, wherein the diisocyanate compound is one or more selected from paraphenylene diisocyanate, tolylene diisocyanate, tolidine diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate. system resin composition.
[5] The polyester-based resin composition according to any one of [1] to [4] above, wherein the organic compound (Y) is a monoalcohol.
[6] The polyester resin composition according to any one of [1] to [5] above, wherein the diol compound is one or more selected from polyether polyols, polyester polyols, polycarbonate polyols and polyurethane polyols. .
[7] Any of the above [1] to [6], wherein the polyester resin (A) is one or more selected from polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polylactic acid and polyhydroxyalkanoic acid. 1. The polyester-based resin composition according to claim 1.

According to the present invention, it is possible to obtain a polyester-based resin composition in which the generation of isocyanate gas due to heat during melt-kneading and molding is suppressed, and which is more excellent in hydrolysis resistance than conventional ones. A polyester-based resin composition is provided.

The polyester-based resin composition of the present invention comprises a polyester-based resin (A), a carbodiimide compound (B) represented by the following formula (1), and an organic compound (C) having at least one of an epoxy group and a hydroxyl group. including. The content of the carbodiimide compound (B) is 0.1 to 10 parts by mass with respect to a total of 100 parts by mass of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C), and the carbodiimide compound It is characterized in that the mass ratio of the organic compound (C) to (B) is from 0.1 to 10.0.

In formula (1), R ¹ and R ² are each independently a residue obtained by removing the functional group from the organic compound (Y) having one functional group reactive with an isocyanate group.
R ³ is a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. The diisocyanate compound has a benzene-based aromatic ring directly bonded to the isocyanate group, and does not have a substituent at both ortho-positions of the benzene-based aromatic ring to the isocyanate group. A plurality of R ³ are the same or different from each other.
R ⁴ is a divalent residue obtained by removing two hydroxyl groups from a diol compound. When there are multiple R ⁴ s, each R ⁴ is the same or different.
The organic compound (Y) is one or more selected from monoalcohols, monoamines, monocarboxylic acids and acid anhydrides.
X ¹ and X ² are each independently a bond formed by reaction between the functional group of the organic compound (Y) and the isocyanate group of the diisocyanate compound.
m is a number from 0 to 50, and n is a number from 1 to 50.

The polyester-based resin composition as described above generates less isocyanate gas due to heating during melt-kneading and molding, and provides a polyester-based resin that is superior in hydrolysis resistance to conventional ones.

[Polyester resin (A)]
The polyester resin (A) in the polyester resin composition of the present invention is not particularly limited as long as it is a resin having an ester group. The polyester-based resin (A) may be used alone or in combination of two or more.
The polyester resin (A) is, for example, polycondensation reaction of dibasic acid or its acid anhydride or dibasic acid ester with diol, or polycondensation reaction or ring-opening polymerization of hydroxycarboxylic acid or its cyclic derivative. is obtained as a resin having an ester bond in the main chain.

Examples of the dibasic acid or acid anhydride thereof include phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride. , tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hetic anhydride, endomethylenetetrahydrophthalic anhydride, maleic anhydride, fumaric acid, and itaconic acid.
Examples of the dibasic acid ester include dimethyl terephthalate and dimethyl naphthalenedicarboxylate.

Examples of the diol include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, hydrogenated bisphenol A, bisphenol A-2-hydroxypropyl ether, cyclohexanedimethanol and the like. Polyether glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol and polyhexamethylene ether glycol are also included.

Examples of the hydroxycarboxylic acid or its cyclic derivative include lactic acid, hydroxybutyric acid, lactide, and lactones such as β-propiolactone and δ-valerolactone.

Specific examples of the polyester resin (A) include polyethylene terephthalate (hereinafter abbreviated as "PET"), polybutylene terephthalate (hereinafter abbreviated as "PBT"), polybutylene succinate, and polybutylene succinate. Adipate, polybutylene adipate terephthalate, polyethylene naphthalate, polyarylate, ethylene terephthalate-isophthalate copolymer, and polyhydroxyalkanoic acid such as polylactic acid and polyhydroxybutyric acid. Among these, PET, PBT, polybutylene succinate, polylactic acid, and polyhydroxyalkanoic acid are preferably used, more preferably PET and PBT, and particularly preferably PBT, from the viewpoint of processability and cost. .

The content of the polyester resin (A) in the polyester resin composition is 80.0 to 80.0 parts per 100 parts by mass in total of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C). It is preferably 99.8 parts by mass, more preferably 85.0 to 99.5 parts by mass, still more preferably 90.0 to 99.0 parts by mass.

[Carbodiimide compound (B)]
The carbodiimide compound (B) in the polyester-based resin composition of the present invention is a compound represented by the following formula (1).
By adding and mixing such a carbodiimide compound to the polyester resin (A), generation of isocyanate gas due to heat during melt-kneading and molding of the polyester resin composition can be suppressed. Further, by adding and mixing the carbodiimide compound (B) together with the organic compound (C) to the polyester resin (A), the polyester resin (A) can be imparted with better hydrolysis resistance than conventionally. can.

< ^R1 and ^R2 >
R ¹ and R ² in the formula (1) are residues obtained by removing the functional group from the organic compound (Y) having one functional group reactive with an isocyanate group. The organic compound (Y) is a terminal blocking agent that blocks terminal isocyanate groups in the compound represented by the formula (1). Said R ¹ and said R ² may be the same or different.

The organic compound (Y) is one or more selected from monoalcohols, monoamines, monocarboxylic acids and acid anhydrides. The organic compound (Y) may be one of these alone, or two or more of them.

In the case of monoalcohols, the functional group is a hydroxyl group, and the reaction between the functional group and the isocyanate group forms a urethane bond. In the case of monoamines, the functional group is an amino group, and the reaction of the functional group with an isocyanate group forms a urea bond. In the case of monocarboxylic acids, the functional group is a carboxy group, and the reaction of the functional group with an isocyanate group forms an amide bond. In the case of an anhydride, the functional group is an anhydride, and the reaction of the functional group with an isocyanate group forms an imide bond. Bonds formed by reaction of these functional groups with isocyanate groups correspond to X ¹ and X ² in the formula (1).

Examples of the monoalcohol include, for example, aliphatic alcohols such as methanol, ethanol, isopropanol, octanol and dodecanol; alicyclic alcohols such as cyclohexanol; (poly)ethylene glycol monomethyl ether, (poly)propylene glycol monomethyl ether and the like ( poly)ether monools, and the like.
Examples of the monoamine include primary amines such as butylamine and cyclohexylamine; and secondary amines such as diethylamine, dibutylamine and dicyclohexylamine.
Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, isovaleric acid, hexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, linoleic acid, linolenic acid, and benzoic acid. is mentioned.
Examples of the acid anhydride include phthalic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, and benzoic anhydride.

Of these organic compounds (Y), monoalcohols have high reactivity with isocyanate groups and are easy to handle as the terminal blocking agent during synthesis of the carbodiimide compound (B). It is preferable from the viewpoint of effectively suppressing isocyanate gas generated by decomposition. Among them, isopropanol, octanol, and cyclohexanol are preferable from the viewpoint of ease of handling. Further, from the viewpoint of suppressing volatilization of organic substances, dodecanol is preferable.

< ^X1 and ^X2 >
X ¹ and X ² in the formula (1) each independently represent a bond formed by reacting the functional group of the organic compound (Y) with the isocyanate group of the diisocyanate compound derived from R ³ . ing. As described above, X ¹ and X ² are bonds corresponding to the organic compound (Y) and may be the same or different.

^<R3>
R ³ in the formula (1) is a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. The diisocyanate compound is an aromatic diisocyanate having a benzene aromatic ring directly bonded to the isocyanate group. The diisocyanate compound has one or more benzene-based aromatic rings, and the two isocyanate groups are directly bonded to the same or different benzene-based aromatic rings, respectively. The benzene-based aromatic ring to which each isocyanate group is bonded does not have a substituent at both positions ortho to the bonding position of the isocyanate group. That is, the benzene-based aromatic ring to which each isocyanate group is bonded either has a substituent at only one of the ortho-positions to the bonding position of the isocyanate group, or does not have a substituent at both.
A plurality of R ³ in the formula (1) may be the same or different.

The compound derived from R ³ is an aromatic diisocyanate as described above, and the carbodiimide compound (B) has a carbodiimide group directly bonded to a benzene aromatic ring. It is considered that even if the carbodiimide equivalent is larger than that of the aliphatic carbodiimide, good hydrolysis resistance can be imparted to the polyester resin.

Examples of aromatic carbodiimide compounds that have been widely used in the past include polymers of 2,4,6-triisopropylbenzene-1,3-diyl diisocyanate (poly(1,3,5-triisopropylphenylene-2,4 -carbodiimide)), stabaxol (registered trademark) P100 (manufactured by Rhein Chemie). This compound has isopropyl groups at both ortho-positions to the carbodiimide group of the benzene aromatic ring directly bonded to the carbodiimide group. The free isocyanate group generated by the decomposition of the compound by heating during melt-kneading or molding when added to a polyester resin has low reactivity due to the effects of steric hindrance of the isopropyl group. It is considered to be easily volatilized.

In contrast, in the carbodiimide compound (B) of the present invention, both ortho positions of the benzene-based aromatic ring directly bonded to the carbodiimide group with respect to the carbodiimide group have no substituents, or only one of them has a structure with a substituent in For this reason, even when the carbodiimide compound (B) is decomposed by heating during melt kneading or molding processing of the polyester resin composition of the present invention to generate free isocyanate groups, the polyester resin composition has high reactivity. It is presumed that it easily reacts with the organic compound (C) in the resin composition and suppresses the generation of isocyanate gas.

Examples of diisocyanate compounds derived from R ³ include paraphenylene diisocyanate, tolylene diisocyanate (hereinafter abbreviated as "TDI"), tolidine diisocyanate, diphenylmethane diisocyanate (hereinafter abbreviated as "MDI"), naphthalene diisocyanate, and the like. The diisocyanate compound may be used alone or in combination of two or more. Among these, MDI is preferable from the viewpoint of suppressing the generation of isocyanate gas due to heat during melt-kneading and molding of the polyester-based resin composition.

TDI has two isomers, 2,4-TDI and 2,6-TDI. Although the types of these isomers are not particularly limited, they are usually a mixture of 2,4-TDI and 2,6-TDI from the viewpoint of availability, etc., and 2 , 4-TDI in an amount of 75 to 85 mol % is preferably used.

MDI has three isomers, 2,2'-MDI, 2,4'-MDI and 4,4'-MDI. The types of these isomers are not particularly limited, but usually, from the viewpoint of availability, etc., a mixture of 2,4'-MDI and 4,4'-MDI, and a simple substance of 4,4'-MDI is preferred. A mixture of 2,4'-MDI and 4,4'-MDI is more preferable from the viewpoint of suppressing the increase in melt viscosity of the carbodiimide compound (B).
In the mixture of 2,4′-MDI and 4,4′-MDI, the molar content of 2,4′-MDI in 100 mol % of the mixture is preferably 30 to 70 mol %, more preferably 40 mol %. ~65 mol%, more preferably 50 to 60 mol%.

^<R4>
R ⁴ in the formula (1) is a divalent residue obtained by removing two hydroxyl groups from the diol compound. A plurality of R ⁴ in the formula (1) may be the same or different.

The diol compound is a compound having two hydroxyl groups, and each of these two hydroxyl groups reacts with the isocyanate group of the diisocyanate compound to form a urethane bond. As a result, the carbodiimide compound (B) has a structure in which a urethane bond is introduced into the carbodiimide segment.
By introducing this urethane bond, the carbodiimide compound (B) is more compatible with the polyester resin (A) than when the urethane bond is not introduced, and melt-kneading and molding of the polyester resin composition. It is presumed that local crosslinking reaction of the polyester resin (A) is less likely to occur during heating, and an increase in melt viscosity is suppressed.

The diol compound may be a low-molecular-weight compound or a high-molecular-weight compound. However, in order to impart good hydrolysis resistance to the polyester resin (A) by the carbodiimide compound (B), it is preferable that the carbodiimide equivalent of the carbodiimide compound (B) is not too large. The molecular weight of the diol compound is preferably 100 to 40,000, more preferably 150 to 10,000, still more preferably 200 to 2,000, from the viewpoint of appropriate solution viscosity and melt viscosity of the resin composition.
When the diol compound is a polymer compound, the molecular weight can be measured by gel permeation chromatography as a number average molecular weight Mn (converted to standard polystyrene).

Examples of the diol compound include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, Aliphatic diols such as neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-dihydroxy-2-butene; cyclohexanediol, cyclohexanedimethanol , alicyclic diols such as hydrogenated bisphenol A; aromatic diols such as bishydroxyethoxybenzene, xylene glycol and bis(2-hydroxyethyl)terephthalic acid. Also included are polymers such as polyether polyols such as polyalkylene glycol, polyester polyols, polycarbonate polyols, polyurethane polyols, and diol-modified silicones. Among these, polyether polyols, polyester polyols, polycarbonate polyols, and polyurethane polyols are preferred from the viewpoint of compatibility with the polyester resin (A) and imparting good hydrolysis resistance to the polyester resin (A). , more preferably polyester polyols.

<m>
m in the formula (1) is a number of 0 to 50, preferably greater than 0 and 20 or less, and more preferably a number of 1 to 10.
When ^{m is 0, the carbodiimide compound (B) is a unit (M) [NH-CO-O-R 4 -O -} CO —NH—R ³ ]. The carbodiimide compound (B) can impart good hydrolysis resistance to the polyester-based resin (A) when used in combination with the organic compound (C) even when the unit (M) is not included. .
When m is greater than 0, the compatibility of the carbodiimide compound (B) with the polyester resin (A) is improved by the unit (M).
When m is larger than 50, the solution viscosity and melt viscosity of the polyester resin composition become too high, which is not preferable.

<n>
n in the formula (1) is a number from 1 to 50, preferably from 2 to 40, more preferably from 3 to 30.
The aforementioned n is the number of units (N) [N=C=N—R ³ ] containing a carbodiimide group generated by polymerization (decarboxylation condensation reaction) of a diisocyanate compound, which is a compound ^derived from R 3 , and It represents a number and is also called the average degree of polymerization of carbodiimide groups.
If n is less than 1, the effect of imparting hydrolysis resistance to the polyester resin (A) by the carbodiimide compound (B) cannot be obtained.
When the n is larger than 50, the carbodiimide compound (B) is difficult to obtain good compatibility with the polyester resin (A), and the molecular weight becomes large, so that the solution of the polyester resin composition It is not preferable because the viscosity and melt viscosity become too large.

When the unit (M) and the unit (N) in the formula (1) are plural in number, the copolymer of each unit may be a block copolymer or a random copolymer. may be In other words, m and n are not limited to the number of units of only the block portion in the block copolymer.

The carbodiimide compound (B) imparts good hydrolysis resistance to the polyester resin (A), and suppresses the generation of isocyanate gas due to heating during melt kneading and molding of the polyester resin composition. From the viewpoint, the carbodiimide equivalent (chemical formula weight per mol of carbodiimide group) is preferably 200-1500, more preferably 220-1000, still more preferably 250-700.

The content of the carbodiimide compound (B) in the polyester resin composition is 0.1 to 10.0 parts per 100 parts by mass in total of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C). It is 0 parts by mass, preferably 0.2 to 7.0 parts by mass, more preferably 0.3 to 5.0 parts by mass.
If the content is less than 0.1 part by mass, sufficient hydrolysis resistance cannot be imparted to the polyester resin (A). On the other hand, when the content exceeds 10.0 parts by mass, it is difficult to suppress the generation of isocyanate gas due to heat during melt-kneading and molding of the polyester-based resin composition. Solution viscosity and melt viscosity tend to increase, and handling is poor.

<Method for producing carbodiimide compound (B)>
The method for producing the carbodiimide compound (B) is not particularly limited, and it can be produced using a known method.
When the carbodiimide compound (B) has a structure in which m in the formula (1) is 0, that is, does not contain the unit (M) [NH--CO--O--R ⁴ --O--CO--NH--R ³ ] , for example, the synthesis methods shown in the following (1) to (3). Among these synthesis methods, the method (2) is preferable from the viewpoint of production efficiency of the carbodiimide compound (B).
(1) The diisocyanate compound is subjected to a carbodiimidation reaction in the presence of a catalyst to obtain an isocyanate-terminated polycarbodiimide, and then an organic compound (Y) (terminal blocking agent) is added to carry out a terminal blocking reaction. Method (2) Mixing the diisocyanate compound and the organic compound (Y) (terminal blocking agent) and performing a carbodiimidation reaction and terminal blocking reaction in the presence of a catalyst Method (3) The diisocyanate compound and the organic compound ( Y) A method of reacting (terminal blocking agent) to conduct a terminal blocking reaction of isocyanate groups, followed by a carbodiimidation reaction in the presence of a catalyst.

Further, the carbodiimide compound (B) has a structure in which m in the formula (1) is greater than 0, that is, the unit (M) [NH-CO-OR ⁴ -O-CO-NH-R ³ ]. In the case of, for example, the synthesis methods shown in (4) to (6) below can be mentioned. Among these synthesis methods, the method (5) is preferable from the viewpoint of production efficiency and the like.
(4) After the diisocyanate compound is subjected to a carbodiimidation reaction in the presence of a catalyst to obtain an isocyanate-terminated polycarbodiimide, then an organic compound (Y) (terminal blocking agent) and the diol compound are added to obtain a urethane. (5) The diisocyanate compound, the diol compound and the organic compound (Y) (terminal blocking agent) are mixed, and urethanization reaction and carbodiimidation reaction are carried out in the presence of a catalyst. and a method of conducting a terminal blocking reaction (6) urethanization reaction of part of the diisocyanate compound and the diol compound to obtain a urethane bond-introduced isocyanate-terminated polycarbodiimide, and then the urethane bond-introduced isocyanate-terminated polycarbodiimide, the above A method of mixing the remainder of the diisocyanate compound and the organic compound (Y) (terminal blocking agent) and performing carbodiimidation reaction and terminal blocking reaction in the presence of a catalyst

The carbodiimidation reaction is preferably, for example, a decarboxylation condensation reaction of the diisocyanate compound in the presence of a carbodiimidation catalyst.
Examples of the carbodiimidation catalyst include 1-phenyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3 and phosphorene oxides such as -methyl-2-phospholene-1-oxide and 3-phospholene isomers thereof. Among these, 3-methyl-1-phenyl-2-phospholene-1-oxide is preferred from the viewpoint of reactivity, availability, and the like.
The amount of the carbodiimidation catalyst used is generally preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and still more preferably 0.2 parts by mass, based on 100 parts by mass of the diisocyanate compound. ~1 part by mass.

The decarboxylation condensation reaction of the diisocyanate compound can be carried out in a solvent or without a solvent. Solvents used include, for example, alicyclic ethers such as tetrahydrofuran, 1,3-dioxane and dioxolane; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; chlorobenzene, dichlorobenzene, trichlorobenzene, perchlene and trichloroethane. , dichloroethane and other halogenated hydrocarbons; cyclohexanone and the like. These may be used alone or in combination of two or more.
When the reaction is carried out in a solvent, the concentration of the diisocyanate compound is preferably 5-55% by mass, more preferably 5-20% by mass.

The reaction temperature of the decarboxylation condensation reaction is appropriately set depending on the appropriate acceleration of the reaction, the degree of polymerization of the carbodiimide groups, and the like. Usually, it is preferably 20 to 200°C, more preferably 30 to 170°C, still more preferably 40 to 150°C. When the reaction is carried out in a solvent, the temperature is preferably within the range of 40° C. to the boiling point of the solvent.
Moreover, the reaction time is appropriately set according to the reaction temperature, the degree of polymerization of the carbodiimide group, and the like. Generally, it is preferably 0.5 to 100 hours, more preferably 1 to 70 hours, still more preferably 2 to 30 hours.
Moreover, it is preferable to carry out the reaction in an atmosphere of an inert gas such as nitrogen gas or rare gas.

The reaction temperature for the urethanization reaction and the terminal blocking reaction is appropriately set within a range capable of suppressing side reactions and promoting the reaction. Generally, it is preferably 20 to 200°C, more preferably 30 to 170°C, still more preferably 40 to 150°C.
In addition, the reaction time is appropriately set within a range in which the reaction temperature and side reactions can be suppressed. Generally, it is preferably 0.1 to 20 hours, more preferably 0.5 to 10 hours, still more preferably 1 to 3 hours.

[Organic compound (C)]
The organic compound (C) in the polyester-based resin composition of the present invention is a compound having at least one of an epoxy group and a hydroxyl group.
By adding and mixing such a compound together with the carbodiimide compound (B) to the polyester resin (A), the polyester resin (A) can be imparted with better hydrolysis resistance than conventionally.

The organic compound (C) is a compound having an epoxy group and/or a hydroxyl group. Hydroxy compounds having a formula weight per mole of 170 to 750 are preferred. Among these, single 1 type may be sufficient and 2 or more types may be used together.
When the epoxy equivalent is 170 or more, an increase in solution viscosity and melt viscosity due to heating during melt kneading and molding of the polyester resin composition is suppressed. Further, if the epoxy equivalent is 750 or less, it is preferable from the viewpoint of imparting good hydrolysis resistance to the polyester resin (A).
The epoxy equivalent is more preferably 170-500, more preferably 180-300.
As for the value of the hydroxyl group equivalent, the same explanation as the value of the epoxy equivalent can be said.
In addition, the said epoxy equivalent can be measured by the method according to description of JISK7236:2001. Also, the hydroxyl equivalent can be obtained from the hydroxyl value measured by the method described in JIS K 1557-1:2007.

Examples of the epoxy compound include bisphenol type epoxy resins such as bisphenol A type, bisphenol F type, bisphenol S type, bisphenol AD type, tetrabromobisphenol A type; Novolak type epoxy resins such as novolak type, brominated phenol novolak type, alkylphenol novolak type, bisphenol S novolak type, alkoxy group-containing novolak type, brominated phenol novolak type and the like can be mentioned. In addition, bifunctional epoxy resins such as phenol aralkyl type epoxy resin (epoxidized Zyloc resin), biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, stilbene type epoxy resin, alicyclic such as hydrogenated bisphenol A type epoxy resin formula epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, biphenyl modified novolak type epoxy resin epoxides), sulfur-containing epoxy resins, resorcinol diglycidyl ether, hydroquinone diglycidyl ether, catechol diglycidyl ether, triglycidyl disocyanurate and the like.

Examples of the hydroxy compound include long-chain alkyl alcohols having 12 or more carbon atoms, such as lauryl alcohol, cetanol, and stearyl alcohol. Examples of compounds having an epoxy group and a hydroxyl group include phenoxy resins such as bisphenol A type phenoxy resins, bisphenol A/bisphenol F type copolymerized phenoxy resins, and phosphorus-modified phenoxy resins.

Among these, the organic compound (C) is preferably solid at 25° C. and 1 atm, that is, at normal temperature and normal pressure, from the viewpoint of ease of handling when added and mixed in the polyester resin composition.

The content of the organic compound (C) in the polyester-based resin composition is such that the mass ratio of the organic compound (C) to the carbodiimide compound (B) is 0.1 to 10.0, preferably 0.2 to 9. 0.0, more preferably 0.3 to 8.0.
When the mass ratio is less than 0.1, the hydrolysis resistance of the resulting polyester resin tends to decrease over time. On the other hand, when the mass ratio exceeds 10.0, the physical properties of the polyester-based resin (A) are impaired, and hydrolysis resistance is not sufficiently imparted.

[Method for producing a polyester-based resin composition]
The polyester-based resin composition can be obtained by melt-kneading the polyester-based resin (A), the carbodiimide compound (B), and the organic compound (C). At this time, a mixture obtained by mixing the polyester resin (A) and the carbodiimide compound (B) in advance may be melt-kneaded, or the carbodiimide compound (B) may be added to the melted polyester resin (A). may be kneaded. Alternatively, the polyester resin (A) may be melt-kneaded with a resin compound such as a masterbatch prepared by any of these methods.
By adding the carbodiimide compound (B) and the organic compound (C), the polyester-based resin composition of the present invention hardly generates isocyanate gas even during melt-kneading as described above, and does not deteriorate the working environment. can be made In addition, since an increase in melt viscosity is suppressed, the working efficiency of melt-kneading can be improved, and the manufacturing efficiency is also excellent.

In addition to the carbodiimide compound (B) and the organic compound (C), the polyester resin (A) includes, for example, antioxidants, flame retardants, ultraviolet absorbers, and coloring agents known to be applied to polyester resins. may be added within a range that does not impair the effects of the present invention. That is, the polyester-based resin composition may contain additives such as those described above, if necessary, from the viewpoint of the performance required for its use.
In this case, the total content of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C) in the polyester resin composition is preferably 90% by mass or more, more preferably 92% by mass. % or more, more preferably 95 mass % or more.

The melt-kneading means is not particularly limited, and a known kneader can be used. Examples of the kneader include a single-screw extruder, a twin-screw extruder, and a roll mixer.
The temperature during melt-kneading is appropriately adjusted according to the type of the polyester resin (A), but is usually about 150 to 350°C.

Production of polyester resin products using the polyester resin composition can be carried out using known molding methods such as injection molding, film molding, blow molding and foam molding. At a temperature equal to or higher than the melting temperature of the polyester-based resin (A), it can be molded into various forms such as film, sheet and block.
A polyester resin product molded in this way using the polyester resin composition of the present invention is excellent in hydrolysis resistance.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.

[Synthesis of carbodiimide compound (B)]
Details of each raw material used in the synthesis examples below are shown below.
<Diisocyanate compound>
A mixture of 2,4'-MDI (54 mol%) and 4,4'-MDI (46 mol%): "Millionate NM" manufactured by Tosoh Corporation 2,4-TDI (80 mol%) and 2, A mixture of 6-TDI (20 mol%): "Cosmonate (registered trademark) T-80", manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd. 4,4'-MDI: "Millionate MT", manufactured by Tosoh Corporation HMDI: Dicyclohexylmethane-4,4'-diisocyanate, "Desmodur (registered trademark) W", manufactured by Sumika Covestro Urethane Co., Ltd. <Organic compound (Y) (end blocking agent)>
・IPA: isopropanol, manufactured by Kanto Chemical Co., Ltd. ・OA: 2-ethylhexanol (octanol), manufactured by Mitsubishi Chemical Corporation <Diol compound>
・ Polyester polyol: "Maximol (registered trademark) RFK-505", manufactured by Kawasaki Chemical Industry Co., Ltd.

(Synthesis example 1)
100 parts by mass of a mixture of 2,4'-MDI (54 mol%) and 4,4'-MDI (46 mol%), 6.9 parts by mass of IPA, and 3-methyl-1-phenyl-2- as a carbodiimidation catalyst 0.5 part by mass of phosphorene-1-oxide was placed in a reaction vessel equipped with a reflux tube and a stirrer, and stirred and mixed at 110° C. for 2 hours under a nitrogen stream.
Infrared absorption (IR) spectrum measurement (measuring device: Fourier transform infrared spectrophotometer "FTIR-8200PC" manufactured by Shimadzu Corporation; hereinafter the same) showed an absorption peak of the isocyanate group around a wavelength of 2270 cm ^-1 . After confirming that it had disappeared, a carbodiimide compound (B1) (m=0, n=6) was obtained.

(Synthesis example 2)
100 parts by mass of a mixture of 2,4'-MDI (54 mol%) and 4,4'-MDI (46 mol%), 6.9 parts by mass of IPA, and 25.3 parts by mass of polyester polyol were added to a reflux tube and a stirrer. The mixture was placed in a reaction vessel with a nitrogen atmosphere and stirred and mixed at 60° C. for 1 hour.
Next, 0.5 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide was added as a carbodiimidization catalyst, and mixed with stirring at 100° C. for 3 hours.
It was confirmed by IR spectrum measurement that the absorption peak of the isocyanate group around a wavelength of 2270 cm ^-1 had disappeared, and a carbodiimide compound (B2) (m=1, n=5) was obtained.

(Synthesis Examples 3 and 4)
Carbodiimide compounds (B3) and (B4) were obtained in Synthesis Example 2 in the same manner as in Synthesis Example 2 except that the composition of each raw material was changed as shown in Table 1 below.

(Synthesis Example 5)
A carbodiimide compound (B5) (aliphatic carbodiimide) was obtained in the same manner as in Synthesis Example 1 except that the diisocyanate compound in Synthesis Example 1 was changed to HMDI to have the raw material composition shown in Table 1 below.

[Production of polyester resin composition]
Details of each raw material used in the following examples and comparative examples are shown below. The epoxy equivalent and hydroxyl equivalent of the organic compound (C) below are calculated values or catalog values.
<Polyester resin (A)>
(A1) PBT resin: "Novaduran (registered trademark) 5010L", manufactured by Mitsubishi Engineering-Plastics Corporation (A2) PET resin: "TRN-8550FF", manufactured by Teijin Chemicals <Carbodiimide compound (B)>
(B1) to (B5): those produced in Synthesis Examples 1 to 5 (B6) Poly(1,3,5-triisopropylphenylene-2,4-carbodiimide): "Stabaxol (registered trademark) P100", Rhein Chemie Made by <organic compound (C)>
(C1) cresol novolac type epoxy resin: "Epiclon (registered trademark) N-695" manufactured by DIC Corporation, epoxy equivalent 215
(C2) Bisphenol A type epoxy resin: "Epiclon (registered trademark) 860" manufactured by DIC Corporation, epoxy equivalent 240
(C3) stearyl alcohol: "Calcol (registered trademark) 8098" manufactured by Kao Corporation, hydroxyl equivalent 270
(C4) Phenoxy resin: "YP-50S", manufactured by Nippon Steel Chemical & Materials Co., Ltd., hydroxyl equivalent 284

(Example 1-1)
Using a lab mixer (“Segment Mixer KF70V”, manufactured by Toyo Seiki Seisakusho Co., Ltd., Laboplastomill (registered trademark); hereinafter the same), 98.5 parts by mass of PBT resin is melted at 250 ° C., and then carbodiimide 1.0 parts by mass of compound (B1) and 0.5 parts by mass of organic compound (C1) were added and kneaded for 3 minutes to produce a polyester-based resin composition (PBT resin composition).

(Examples 1-2 to 1-26, Comparative Examples 1-2 to 1-13)
In Example 1-1, each polyester resin composition (PBT resin composition) was produced.

(Comparative Example 1-1)
A blank of only the PBT resin to which the carbodiimide compound (B) and the organic compound (C) were not added was used as Comparative Example 1-1.

(Example 2-1)
After melting 98.5 parts by mass of PET resin at 280° C. using a lab mixer, 1.0 part by mass of carbodiimide compound (B1) and 0.5 parts by mass of organic compound (C1) were added and kneaded for 3 minutes. Then, a polyester-based resin composition (PET resin composition) was produced.

(Examples 2-2 to 2-26, Comparative Examples 2-2 to 2-13)
In Example 2-1, each polyester resin composition (PET resin composition) was produced.

(Comparative Example 2-1)
Comparative Example 2-1 was a blank made of only PET resin to which the carbodiimide compound (B) and the organic compound (C) were not added.

[Measurement evaluation]
Each polyester resin composition obtained in the above examples and comparative examples was measured and evaluated for the items shown below. These measurement evaluation results are summarized in Tables 2 and 3 below.

<Isocyanate gas generation>
The melt-kneaded polyester resin composition is heated at 300° C. for 20 minutes, and the isocyanate gas generated is quantitatively analyzed using a gas chromatograph-mass spectrometer (GC-MS) (“6890 GC system” manufactured by Agilent Technologies). gone.
It is preferable that the detected amount (generated amount) of isocyanate gas is as small as possible. The evaluation results shown in Tables 2 and 3 below are based on the following evaluation criteria.
〔Evaluation criteria〕
A: Detected amount of isocyanate gas is less than 500 ppm B: Detected amount of isocyanate gas is 500 ppm or more and less than 1000 ppm C: Detected amount of isocyanate gas is 1000 ppm or more

<Hydrolysis resistance>
(1) PBT Resin Composition The melt-kneaded PBT resin composition was flat-pressed at 250° C. to form a sheet with a thickness of about 300 μm, and then a strip sheet with a width of 10 mm and a length of 70 mm was produced.
The tensile strength of this strip sheet was measured with a tensile tester (“3365”, manufactured by Instron; temperature 20±5° C. (room temperature); hereinafter the same).
Further, the strip sheet was set in a highly accelerated life tester ("EHS-210M", manufactured by Espec Co., Ltd., constant temperature and humidity chamber; temperature 121° C., relative humidity 100%) to perform wet heat treatment. After 72 hours, 120 hours, and 168 hours from the start of wet heat treatment, the tensile strength of each strip sheet was measured with a tensile tester.
Before the wet heat treatment, after 72 hours, after 120 hours, and after 168 hours, the average value of the measured tensile strength of 5 strip sheets was calculated.
The ratio of the average tensile strength after 72 hours to the average tensile strength (reference value) before wet heat treatment was calculated as the strength retention after 72 hours. After 120 hours and 168 hours, each strength retention rate was obtained in the same manner.

The strength retention rate is an index for evaluating the hydrolysis resistance of polyester resins, and the higher the value, the more tensile strength is retained even after wet heat treatment, and after a longer time. If the value of is large, it can be said that the hydrolysis resistance of the polyester resin is superior.

(2) PET Resin Composition The melt-kneaded PET resin composition was flat-pressed at 280° C. to form a sheet with a thickness of about 300 μm, and then a strip sheet with a width of 10 mm and a length of 70 mm was produced.
In the measurement evaluation of the hydrolysis resistance of the PBT resin composition in (1) above, the timing of measuring the tensile strength of each strip sheet was changed to 40 hours, 72 hours, and 96 hours after the start of the wet heat treatment. Otherwise, each strength retention rate was obtained in the same manner.

As can be seen from the measurement evaluation results shown in Tables 2 and 3, the polyester-based resin composition of the present invention can be melt-kneaded or heated during molding by the combined addition of the carbodiimide compound (B) and the organic compound (C). It was confirmed that the generation of isocyanate gas was suppressed and a polyester resin excellent in hydrolysis resistance could be obtained. In particular, it was recognized that the effect of improving the hydrolysis resistance of the PBT resin was excellent.

Claims (6)

A polyester resin (A), a carbodiimide compound (B) represented by the following formula (1), and an organic compound (C) having at least one of an epoxy group and a hydroxyl group,
The content of the carbodiimide compound (B) is 0.1 to 10.0 parts by mass with respect to a total of 100 parts by mass of the polyester resin (A), the carbodiimide compound (B) and the organic compound (C). can be,
A polyester-based resin composition, wherein the mass ratio of the organic compound (C) to the carbodiimide compound (B) is 0.1 to 10.0.

(In the formula, R ¹ and R ² are each independently a residue obtained by removing the functional group from the organic compound (Y) having one functional group reactive with an isocyanate group.
R ³ is a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. The diisocyanate compound has a benzene-based aromatic ring directly bonded to the isocyanate group, and does not have a substituent at both ortho-positions of the benzene-based aromatic ring to the isocyanate group. A plurality of R ³ are the same or different from each other.
R ⁴ is a divalent residue obtained by removing two hydroxyl groups from a diol compound. When there are multiple R ⁴ s, each R ⁴ is the same or different. The diol compound is a polyester polyol.
The organic compound (Y) is one or more selected from monoalcohols, monoamines, monocarboxylic acids and acid anhydrides.
X ¹ and X ² are each independently a bond formed by reaction between the functional group of the organic compound (Y) and the isocyanate group of the diisocyanate compound.
m is a number from 0 to 50, and n is a number from 1 to 50. ) The organic compound (C) is one or more selected from an epoxy compound having an epoxy equivalent of 170 to 750 and a hydroxy compound having a hydroxyl group equivalent of 170 to 750. The polyester resin composition according to claim 1. . The polyester-based resin composition according to claim 1 or 2, wherein the organic compound (C) is solid at 25°C and 1 atm. The polyester resin composition according to any one of claims 1 to 3, wherein the diisocyanate compound is one or more selected from paraphenylene diisocyanate, tolylene diisocyanate, tolidine diisocyanate, diphenylmethane diisocyanate and naphthalene diisocyanate. The polyester-based resin composition according to any one of claims 1 to 4, wherein the organic compound (Y) is a monoalcohol. The polyester-based resin (A) is one or more selected from polyethylene terephthalate, polybutylene terephthalate, polybutylene succinate, polylactic acid and polyhydroxyalkanoic acid, according to any one of claims 1 to 5 . Polyester resin composition.