JPH04366160A - Polyester composition - Google Patents

Abstract

PURPOSE:To obtain a polyester composition improved in heat resistance and mechanical properties by mixing a specified polyester with a hindered phenolic antioxidant, a sulfur-containing antioxidant and a polycarbodiimide. CONSTITUTION:A polyester obtained by copolymerizing an aliphatic dicarboxylic acid of formula I with an aliphatic diol and a dihydroxy compound of formula II (wherein R<1> and R<2> are each alkylene; p is 3 or 4; and g is 0, 1 or greater) and/or 0.1-30mol% monohydroxy compound of formula III (wherein R<3> is alkylene; l is 2 or 3; and m is 0, 1 or greater) is mixed with 0.05-1.00wt.% hindered phenolic antioxidant of formula IV (wherein R<4> is sec. or tert. alkyl; and R<5> is H or alkyl), 0.05-1.6wt.% sulfur-containing antioxidant of formula V (wherein R<5> and R<6> are each an aromatic or aliphatic substituent; and t is 1-3) and 0.5-4.0wt.% polycarbodiimide.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition useful as a thermoplastic elastomer, and more particularly to a polyester composition having excellent heat resistance and mechanical properties.

0002

BACKGROUND OF THE INVENTION Thermoplastic elastomers exhibit rubber elasticity at room temperature and are moldable, so they are widely used in various industrial products. In particular p-terphenyl or p-
Polyesters containing dihydroxy or monohydroxy compounds having a quarterphenyl skeleton have been obtained as thermoplastic elastomers with excellent mechanical properties, and are described in, for example, JP-A-3-103433). The above-mentioned polyester has excellent heat deformation resistance, and is therefore expected to be used in high-temperature atmospheres.

0003

[Problems to be Solved by the Invention] However, when the polyester and other additives are melt-kneaded, molded, or used at high temperatures, the polyester is decomposed and its molecular weight decreases, resulting in poor mechanical properties of the resulting molded product. The disadvantage is that it decreases. Particularly when it is carried out at high temperature and high humidity, the molecular weight decreases markedly.

The present invention aims to solve the above-mentioned problems, and its object is to provide a polyester composition which has excellent heat resistance and whose mechanical properties do not deteriorate even when exposed to high temperatures for a long period of time.

[0005]

[Means for Solving the Problems] The polyester composition of the present invention comprises an aliphatic dicarboxylic acid represented by the following general formula [I], an aliphatic diol, and a dihydroxy compound represented by the following general formula [II]. A polyester containing at least one of the monohydroxy compounds represented by the following general formula [III] as a main component, a polyester having the following general formula [I
A polyester composition containing a hindered phenolic antioxidant having a partial structure represented by [V], a sulfur antioxidant represented by the following general formula [V], and a polycarbodiimide, the polyester composition comprising: 0.05% to 1% by weight of the hindered phenolic antioxidant
．． 00% by weight, sulfur-based antioxidant from 0.05% by weight
1.6% by weight, and 0.5% by weight of the polycarbodiimide
It is characterized by containing 4.0% by weight each,
This achieves the above objective.

[0006]

[C6]

(In the formula, n represents an integer of 0 to 10.)

[0008]

[C7]

(In the formula, R1 and R2 each represent an alkylene group, p is 3 or 4, and q and r are independently 0.
or an integer greater than or equal to 1).

0010

[Chemical formula 8]

(In the formula, R3 represents an alkylene group, l is 2 or 3, and m is an integer of 0 or 1 or more)
.

0012

[Chemical formula 9]

(In the formula, R4 represents a secondary or tertiary alkyl group, and R5 represents hydrogen or an alkyl group.)

[0014]

[Chemical formula 10]

(In the formula, R6 and R7 independently represent an aromatic or aliphatic substituent, and t represents an integer of 1 to 3).

Next, the present invention will be explained in detail.

The polyester used in the present invention comprises an aliphatic dicarboxylic acid represented by the above general formula [I], an aliphatic diol, a dihydroxy compound represented by the above general formula [II] and the above general formula [III]. The main component is one of the monohydroxy compounds shown.

The aliphatic dicarboxylic acid used in the present invention is represented by the general formula [I] and has 1 carbon number.
~10. If an aliphatic carboxylic acid having more than 10 carbon atoms is used, the physical properties of a molded article obtained using this polyester will deteriorate.

Examples of the aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, gludaric acid, adipic acid, suberic acid, and sebacic acid.

Aliphatic diols used in the present invention include glycols and polyalkylene oxides. Examples of the above glycol include ethyl glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, cyclopentane-1,2-diol , cyclohexane-1,2-diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, etc. These may be used alone, or two types may be used. The above may be used in combination.

[0021] Examples of the above polyalkylene oxide include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyhexamethylene oxide, etc., and these may be used alone or in combination of two or more. Good too. The number average molecular weight of the polyalkylene oxide is preferably from 100 to 20,000, more preferably from 500 to 5,000. If the number average molecular weight becomes too large, physical properties such as thermal stability of the polyester produced will deteriorate, and if it becomes too small, the ability to impart flexibility to the polyester produced will decrease.

The dihydroxy compound used in the present invention is
It is a liquid crystal low molecular compound represented by the above general formula [II], and the alkylene groups R1 and R2 are preferably ethylene or propylene groups, and q and r
is preferably 0 or 1. For example, 4,4''-dihydroxy-p-terphenyl represented by the following formula [VI], 4,4''-dihydroxy-p-terphenyl represented by the following formula [VII]
P-quarterphenyl, 4,4'''-di(2-hydroxyethoxy)-p-quarterphenyl represented by the following formula [VIII], and the like are preferably used. 4,4''-
The transition temperature of dihydroxy-p-terphenyl [VI] from the crystalline state to the liquid crystalline state is 260°C, and 4,4''
'-dihydroxy-p-quarterphenyl [VII]
that of 336°C and 4,4'''-di(2-hydroxyethoxy)-p-quarterphenyl [VIII
] is 403°C. Furthermore, the liquid crystal state refers to a state in which molecules maintain their orientation even in a molten state. The dihydroxy compounds [II] may be used alone or in combination.

[0023]

[Chemical formula 11]

[0024]

[Chemical formula 12]

[0025]

[Chemical formula 13]

Liquid crystal molecules generally have high crystallinity, and as mentioned above, 4,4''-dihydroxy-p-terphenyl [VI], 4,4''-dihydroxy-p-quarterphenyl [VII] and 4,4'''-di(2-hydroxyethoxy)-p-quarterphenyl [VII
Since these dihydroxy compounds [II] and the like have a high transition point from a crystalline state to a liquid crystal state, when these dihydroxy compounds [II] are incorporated into a polymer chain, the polymer exhibits unique properties. That is, since dihydroxy compound [II] exhibits crystallinity and has a high melting point, dihydroxy compound [II]
Even when the amount of compound II] is small, strong and highly heat-resistant physical crosslinks are formed. As a result, it is presumed that a thermoplastic elastomer with high heat resistance can be obtained without impairing the flexibility derived from the soft segment.

The monohydroxy compounds used in the present invention are represented by the general formula [III] and are rigid low-molecular compounds having a paraphenylene skeleton. Melting point is extremely high. Furthermore, the paraphenylene skeleton is known to be effective as a mesogen for low-molecular liquid crystal compounds, and this is because the skeleton has a strong cohesive force not only in the solid state but also in the high temperature state (molten state). This shows that. Therefore, when the above-mentioned monohydroxy compound [III] is incorporated at the end of the polymer, very strong and highly heat-resistant physical crosslinking is produced, and a thermoplastic elastomer with excellent heat resistance is produced.

In the monohydroxy compound represented by the general formula [III], R3 is preferably an ethylene group or a propylene group, and m is preferably 0 or 1. As the above monohydroxy compound [III], for example, 4
-Hydroxy-p-terphenyl, 4-hydroxy-p
-quarterphenyl, 4-(2-hydroxyethoxy)-p-terphenyl, 4-(2-hydroxyethoxy)-p-quarterphenyl, and the like. The monohydroxy compounds [III] may be used alone or in combination.

[0029] The above aliphatic dicarboxylic acid [I], the above aliphatic diol, and the above dihydroxy compound [II]
and a polyester containing at least one of the monohydroxy compounds [III] as a main component,
Polysilicone, lactone, or aromatic hydroxycarboxylic acid having two or more hydroxyl groups may be included as a constituent component.

The above-mentioned polysilicone has two hydroxyl groups, and polysilicone with two hydroxyl groups at the ends of the molecule is preferable, such as dimethylpolysiloxane and diethylpolysiloxane, which have two hydroxyl groups at both ends of the molecule. Examples include siloxane and diphenylpolysiloxane. The number average molecular weight of polysilicone is 100 to 2000, since it becomes difficult to produce aromatic polyester when it becomes large.
0 or less is preferable, more preferably 500 to 5,000
It is as follows.

[0031] The above-mentioned lactone reacts with an acid and a hydroxyl group by ring-opening and adds an aliphatic chain, which gives flexibility to the polyester, and which has four or more carbon atoms in the ring. It is preferable to have a 5- to 8-membered ring, and more preferably a 5- to 8-membered ring. Examples include ε-caprolactone, δ-valerolactone, γ-butyrolactone, enantolactone, caprylolactone, and the like.

The above-mentioned aromatic hydroxycarboxylic acids impart rigidity and liquid crystallinity to polyester, and include salicylic acid, metahydroxybenzoic acid, parahydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, and 3-bromo-benzoic acid. 4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3-methyl-4-hydroxybenzoic acid,
Examples include 3-phenyl-4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxy-4'-carboxybiphenyl, etc., and preferably parahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxy-4'-carboxybiphenyl.

[0033] Further, the polyester may contain an aromatic diol or an aromatic dicarboxylic acid other than the dihydroxy compound [II] as a constituent component in order to improve mechanical properties other than the polyester.

Examples of the aromatic diol include hydroquinone, resorcinol, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4
'--dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfite, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4
, 4'-dihydroxydiphenylmethane, bisphenol A, 1,1-di(4-hydroxyphenyl)cyclohexane, 1,2-bis(4-hydroxyphenoxy)ethane, 1,4-dihydroxynaphthalene, 2,6-dihydroxy Examples include naphthalene.

Examples of the aromatic dicarboxylic acids include isophthalic acid, metal salts of 5-sulfoisophthalic acid, and 4,4'-
Dicarboxybiphenyl, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl sulfide, 4,4'-dicarboxydiphenyl sulfone, 3,3'-dicarboxybenzophenone, 4,4'
-dicarboxybenzophenone, 1,2'-bis(4-
Examples include carboxyphenoxy)ethane, 1,4-dicarboxynaphthalene, and 2,6-dicarboxynaphthalene.

[0036] When the polyester containing the above dihydroxy compound [II], the above aliphatic dicarboxylic acid [I] and the above aliphatic diol as main components is prepared as a thermoplastic elastomer, the content of the dihydroxy compound [II] is small. When the amount increases, the heat resistance of the resulting polyester decreases, and when the amount increases, the elastic modulus increases and the flexibility decreases.
Since it is unsuitable as a thermoplastic elastomer, the content of the dihydroxy compound [II] is preferably 0.1 to 30 mol%, more preferably 0.5 to 20 mol% of the diol component constituting the polyester. The content is more preferably 1.0 to 10 mol%. In addition, when polyalkylene oxide or polysilicone is used as a diol other than aromatic, the constituent unit thereof is counted as one monomer. That is, polyethylene oxide with a polymerization degree of 10 is 1
Count as 0 monomer.

When preparing a polyester containing the above monohydroxy compound [III], the above aliphatic dicarboxylic acid [I] and the above aliphatic diol as main components as a thermoplastic elastomer, the monohydroxy compound [III]
] If the content of the monohydroxy compound [III
] is preferably 0.1 to 30 mol% of the diol component constituting the polyester, more preferably 0.5
It is 20 mol%, more preferably 1.0 to 10 mol%.

[0038] The above dihydroxy compound [II], the monohydroxy compound [III], the above aliphatic dicarboxylic acid [
I] and the polyester containing the above aliphatic diol as a main component is prepared as a thermoplastic elastomer,
Dihydroxy compound [II] and monohydroxy compound [
If the content of the hydroxy compound combined with III) is low, the heat resistance will decrease, and if it is high, the flexibility will decrease and a sufficient increase in molecular weight will not be obtained. Mol% is preferred. In this case, the ratio of the dihydroxy compound [II] and the monohydroxy compound [III] is preferably in a range that satisfies the following: 0<[III]/[II]+[III]<2/3.

The polyester comprising the above-mentioned components can be produced using any generally known polycondensation method. For example, ■ a method in which dicarboxylic acid and a diol component (including aliphatic diols, dihydroxy compounds, monohydroxy compounds, etc.) are directly reacted; ■ a method in which a lower ester of dicarboxylic acid and a diol component are reacted using transesterification. A method for reacting a dicarboxylic acid halide and a diol component in a suitable solvent such as pyridine; ■ A method for reacting a metal alcoholate of a diol component with a dicarboxylic acid halide; ■ A method for reacting a dicarboxylic acid halide with a diol component; Examples include a method of reacting with a dicarboxylic acid using transesterification.

[0040] In the polycondensation, catalysts generally used in producing polyester may be used. This catalyst includes metals such as lithium, sodium, potassium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium, manganese, etc. Examples thereof include organometallic compounds, organic acid salts, metal alkoxides, and metal oxides.

Particularly preferred catalysts are calcium acetate, diacyltinn, tetraacyltinn, dibutyltin oxide, dibutyltin dilaurate, dimethyltin malate,
These are tin dioctanoate, tin tetraacetate, triisobutylaluminum, tetrabutyl titanate, germanium dioxide, and antimony trioxide. Two or more of these catalysts may be used in combination. Furthermore, various stabilizers may be used to improve thermal stability during polymerization.

[0042] Furthermore, in order to efficiently distill off water, alcohol, glycol, etc. produced as by-products during polymerization, it is preferable to reduce the pressure of the reaction system to 1 mmHg or less. The reaction temperature is generally 150-350°C.

[0043] Also, during the polymerization, dihydroxy compound [II
] The structure of the resulting polyester can be controlled by changing the order of addition. For example, if dihydroxy compound [II] is added together with dicarboxylic acid and other diol components, a random copolymer cannot be obtained, and if dihydroxy compound [II] is added in the late stage of polymerization, a block copolymer cannot be obtained. Union will not be obtained. Alternatively, a segment based on the dihydroxy compound [II] is introduced into the molecular chain of the pre-synthesized polyester by removing ethylene glycol or transesterifying the dihydroxy compound [II] or the acetyl compound of the dihydroxy compound [II] under reduced pressure and heating. It is also possible.

The polyester composition of the present invention contains a hindered phenolic antioxidant and a sulfur antioxidant.

The hindered phenolic antioxidant used in the present invention has a partial structure represented by the general formula [IV], for example, 3,9-bis-[2-
(3-(3-t-butyl-4-hydroxy-5-methylphenyl)-propionyloxy)-1,1-dimethylethyl]2,4,6,10-tetraoxaspiro[5,5
]Undecane, triethylene glycol bis[3-(3
-t-butyl-5-methyl-4-hydroxyphenyl)
propionate], 1,6-hexanediol-bis[
3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], tetrakis[methylene(3,5
-di-t-butyl-4-hydroxyhydrocinnamate)]methane, octadecyl-3-(3,5-di-t-
Butyl-4-hydroxyphenyl)propionate, N
, N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-t
-Butyl-4-hydroxy-benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4
,6,-Tris-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis(3,5-t-butyl-4-hydroxybenzylethyl)calcium, tris-(3,5 -di-t-butyl-4-hydroxybenzyl)-isocyanurate, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 2,2-bis[4-( 2-(3,5-di-
Examples include t-butyl-4-hydroxyhydrocinnamoyloxy))ethoxyphenyl]propane, 2,6-di-t-butyl-4-methylphenol, and the like.

The above-mentioned hindered phenolic antioxidant is added in an amount of 0.05 to 1.00% by weight based on the polyester. When the content of the hindered phenolic antioxidant is less than 0.05% by weight, heat resistance decreases. On the other hand, the content of hindered phenolic antioxidant is 1.0
When it exceeds 0% by weight, heat resistance is improved but not effectively, and physical properties such as mechanical strength are reduced.

The sulfur-based antioxidant used in the present invention is represented by the general formula [V], and includes, for example, diralyl-3,3'-thiodibropionate, dimyristyl-3,3' -thiodibropionate, pentaerythryltetrakis (3-laurylthiopropionate),
Examples include ditridecyl-3,3'-thiodibropionate and dioctadecyl disulfide.

The sulfur-based antioxidant is added in an amount of 0.05 to 1.6% by weight based on the polyester. When the content of the sulfur-based antioxidant is less than 0.05% by weight, heat resistance decreases. On the other hand, when the content of the sulfur-based antioxidant exceeds 1.6% by weight, heat resistance is improved but not effective, and physical properties such as mechanical strength are reduced.

The weight ratio of the sulfur-based antioxidant to the hindered phenol-based antioxidant is preferably 0.3 to 6.0. The weight ratio of sulfur-based antioxidant to hindered phenolic antioxidant is less than 0.3 or 6.0
If it exceeds 20%, an effective synergistic effect between the hindered phenol antioxidant and the sulfur antioxidant cannot be obtained.

The total weight of the hindered phenol antioxidant and the sulfur antioxidant is preferably 2% by weight or less based on the polyester. When the sum of the weights of the hindered phenol antioxidant and the sulfur antioxidant exceeds 2% by weight, heat resistance is improved, but not effectively, and physical properties such as mechanical strength are reduced.

The polyester composition of the present invention contains polycarbodiimide.

The polycarbodiimide used in the present invention is a polycarbodiimide having an average of two or more carbodiimides per molecule. These carbodiimides are
It may be aliphatic, alicyclic, or aromatic. For example, poly(tolylcarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(1,3,5,-triisopropyl-2,4 −
phenylenecarbodiimide), etc. Two or more types of polycarbodiimides may be used in combination.

The above polycarbodiimide is added in an amount of 0.5% to 4.0% by weight based on the polyester. When the content of polycarbodiimide is less than 0.5% by weight, heat resistance decreases. On the other hand, when the content of polycarbodiimide exceeds 4.0% by weight, heat resistance is improved but not effectively, and physical properties such as mechanical strength are reduced.

The polyester composition of the present invention can be obtained by a commonly known method. When polymerizing polyester, it is possible to adopt a method in which the monomer, the antioxidant, and the polycarbodiimide are added simultaneously, a method in which the antioxidant and the polycarbodiimide are added in the latter stage of the polymerization, and the like. After polymerization, a melt kneading method is employed to uniformly mix the polyester, the antioxidant, and the polycarbodiimide using a plastomill, extruder, kneader, Banbury mixer, or the like.

Further, the following additives may be added during or after the production of the polyester composition of the present invention within a range that does not impair practicality.

(i) Inorganic fiber: glass fiber, carbon fiber,
Boron fiber, silicon carbide fiber, alumina fiber, amorphous fiber, silicon/titanium/carbon fiber, etc.

(ii) Organic fibers: aramid fibers, etc.

(iii) Inorganic filler: calcium carbonate,
Titanium oxide, mica, talc, etc.

(iv) Flame retardants: hexabromocyclododecane, tris-(2,3-dichloropropyl)phosphate, pentabromophenyl allyl ether, etc.

(v) Ultraviolet absorber: p-tert-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2
'-carboxybenzophenone, 2,4,5-trihydroxybutyrophenone, etc.

(vi) Antioxidants: butylated hydroxyanisole, butylated hydroxytoluene, distearylthiodipropionate, dilaurylthiodipropionate, hindered phenolic antioxidants, etc.

(vii) Antistatic agent: N,N-bis(hydroxyethyl)alkylamine, alkylarylsulfonate, alkylsulfanate, etc.

(viii) Inorganic substances: barium sulfate, alumina, silicon oxide, etc.

(ix) Higher fatty acid salts: sodium stearate, barium stearate, sodium palmitate, etc.

(x) Other organic compounds: benzyl alcohol, benzophenone, etc.

(xi) Crystallization accelerator; highly crystallized polyethylene terephthalate, polytrans-cyclohexanedimethanol terephthalate, etc.

Furthermore, the obtained polyester composition can be mixed with other thermoplastic resins such as polyolefin, modified polyolefin, polystyrene, polyamide, polycarbonate, polysulfone, polyester, etc., or mixed with a rubber component to improve its properties. May be modified.

[0068] The polyester composition obtained in the present invention is
It can be used as a thermoplastic elastomer, and is made into a molded body by melt molding methods such as press molding, extrusion molding, injection molding, and blow molding. The physical properties of the molded product can be changed arbitrarily depending on its constituent components and their blending ratios, making it suitable for use in flexible molded products such as automobile parts, hoses, belts, and packing, as well as paints and adhesives. be done.

[0069]

EXAMPLES The present invention will be explained below based on examples.

Synthesis of polyester 348.4 g (2 mol) of adipinesanmethyl, 298 g (2.4 mol) of ethylene glycol and 4,4'
''-dihydroxy-p-quarterphenyl (hereinafter referred to as
A monomer mixture of 67.7 g (0.2 mol) (abbreviated as DHQ) was added with 200 mg of antimony oxide and 440 mg of calcium acetate as a catalyst, and 1,3,5 as a stabilizer.
-trimethyl-2,4,6-tris(3,5-di-t-
Butyl-4-hydroxybenzyl)benzene 400mg
, tris(2,4-di-t-butylphenyl)phosphite was added. After purging the reaction system with nitrogen, the reaction was carried out at 200° C. for 2 hours to perform transesterification. Next, the temperature of this reaction system was raised to 320°C for 30 minutes, and in this state it was heated to 20°C.
After holding at normal pressure for a minute, the temperature was lowered to 300℃ and 1mmHg
A polycondensation reaction was carried out for 1 hour under reduced pressure as described below to obtain a light gray resin.

[0071] 50.7 g of 4,4'''-dihydroxy-p-quaterphenyl (DHQ) was added to this flask, and the temperature of the flask was raised to 280°C.
Allowed time to react. Next, the distillation port was connected to a vacuum vessel, and the flask was reacted for 1 hour while the pressure inside the flask was reduced to 1 mmHg. During the reaction, ethylene glycol was distilled out, and an extremely viscous liquid was formed in the flask. After the flask was allowed to cool, the glass flask was broken and the product was taken out.

Examples 1 to 2, Comparative Examples 1 to 5 3,9-bis[2-(3-(3-t-butyl-4-
Hydroxy-5-methylphenyl)-propionyloxy)-1,1-dimethylethyl]2,4,8,10-tetraoxaspiro[5,5]undecane (additive 1),
Pentaerythryl tetrakis (3-laurylthiopropionate) (Additive 2) is used as a sulfur-based antioxidant, and poly(1,3,5-triisopropylphenylene-2,4-carbodiimide) (Additive 2) is used as a polycarbodiimide. 8; Sumitomo Bayer Urethane Co., Ltd., Stavaxol P-100) in the weight percentage shown in Table 1 based on polyester.
was added and melt-kneaded for 10 minutes at 220°C using a Brabender Plastograph extruder to obtain a resin composition. Next, injection molding (injection pressure 1500 kgf/c
m2, mold temperature 70°C, cylinder temperature 220°C) to obtain a No. 3 dumbbell.

A heat deterioration resistance test was conducted on the dumbbell pieces obtained in Examples 1 to 2 and Comparative Examples 1 to 5 by the method shown below. The results are shown in Table 1.

Heat Deterioration Resistance Test The dumbbell pieces obtained in a gear oven were left at 170° C. for the predetermined time shown in Table 1. After a predetermined period of time had elapsed, the dumbbell piece was taken out and its elongation retention rate was measured. The elongation retention rate was determined by measuring the tensile elongation at break using Shimadzu Autograph AG-5000 in accordance with JIS K6301, and calculating the ratio before and after the heat resistance test.

[0075]

[Table 1]

From Table 1, it can be seen that the dumbbell pieces obtained from the polyester compositions of Examples 1 and 2 have good heat resistance.

[0077]

Effects of the Invention As is clear from the above explanation, the polyester composition of the present invention can provide a thermoplastic elastomer with excellent heat resistance and mechanical strength.
It can be suitably used for various members.

Claims (1)

[Claims] Claim 1: An aliphatic dicarboxylic acid represented by the following general formula [I], an aliphatic diol, a dihydroxy compound represented by the following general formula [II], and a monohydroxy compound represented by the following general formula [III] A polyester containing at least one of the compounds as a main component, a hindered phenolic antioxidant having a partial structure represented by the following general formula [IV], a sulfur-based antioxidant represented by the following general formula [V] A polyester composition containing an antioxidant and polycarbodiimide, wherein the hindered phenolic antioxidant is 0.05% by weight based on the polyester.
~1.00% by weight, 0.05% to 1.6% by weight of the sulfur-based antioxidant, and 0.5% to 4.0% by weight of the polycarbodiimide, respectively. Polyester composition. embedded image (where n represents an integer of 0 to 10). [Formula 2] (wherein, R1 and R2 each represent an alkylene group, and p
is 3 or 4, and q and r independently represent 0 or an integer of 1 or more). embedded image (wherein R3 represents an alkylene group, l is 2 or 3, and m represents an integer of 0 or 1 or more). embedded image (wherein R4 represents a secondary or tertiary alkyl group, and R5 represents hydrogen or an alkyl group). embedded image (wherein R6 and R7 independently represent an aromatic or aliphatic substituent, and t represents an integer of 1 to 3).