JP2551667B2 - Method for producing polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has properties as a thermoplastic elastomer,
The present invention relates to a method for stably producing a polyester having excellent heat resistance, mechanical strength and moldability.

(Prior Art) Generally, in order for a material to exhibit rubber elasticity, it is necessary that an amorphous polymer whose molecular chain can easily rotate is partially crosslinked. For example, in elastic rubber, sulfur molecules form a network structure by bridging the molecular chains by chemical bonds. In addition to rubber, materials combining various polymer compounds and crosslinking agents have been proposed. A cross-linking process is required to mold these materials, and since they do not exhibit thermoplasticity after being chemically cross-linked, cross-linked materials cannot be molded by injection molding or extrusion.

In recent years, a thermoplastic elastomer that exhibits rubber elasticity at room temperature and is plasticized at high temperature has been developed, and various types of thermoplastic elastomers are manufactured and marketed. This thermoplastic elastomer does not require a long-time cross-linking step unlike the conventional rubber, and can be molded by injection molding or extrusion molding. A characteristic of the molecular structure of thermoplastic elastomers is a cross-link that does not rely on a strong chemical bond, that is, a system that applies some kind of inter-polymer constraint that is effective only at around room temperature, and is a polymer assembly consisting of soft and hard segments. The body is the typical structure of thermoplastic elastomers. The soft segment and the hard segment have different chemical structures from each other. In the hybrid composition of the two, the homogenous parts agglomerate, and the heterogeneous parts form a micro-unbalanced structure in which the phases are separated from each other. The agglutinated portion shows a binding effect between the molecules.

Examples of the thermoplastic elastomer include styrene type, olefin type, urethane type, ester type and amide type. In the styrene series, polystyrene forms a frozen phase as a hard segment and binds between molecular chains, resulting in rubber elasticity. In the olefin system, the polypropylene crystal phase acts as a hard segment. In the urethane type, the polyurethane segment causes physical crosslinks between molecular chains by hydrogen bonds. Further, the ester-based polybutylene terephthalate chain acts as a hard segment, and the amide-based nylon chain such as 6-nylon or 6,6-nylon acts as a hard segment.

(Problems to be Solved by the Invention) As described above, since the thermoplastic elastomer exhibits rubber elasticity at room temperature and can be molded, it is widely used for automobile parts and various industrial products. However, conventional thermoplastic elastomers have lower heat resistance and poorer creep properties than the cross-linking type rubber because they are restricted by the softening melting point of the part because they are cross-linked by physical restraint. Was becoming. For example, Toyobo Co., Ltd.'s Perprene S-9001, which is known as the most heat-resistant ester type among thermoplastic elastomers, has a melting point of 223 ° C and a heat distortion temperature (low load) of 146 ° C. Even in the system, the softening point is 140 ° C at most.

An aliphatic polyester containing a dihydroxy or monohydroxy compound having a p-terphenyl or p-quaterphenyl skeleton as a constituent component has a transition point (melting point) from a crystalline state of this hydroxy compound to a liquid crystal state.
However, since it is extremely high, reflecting its characteristic molecular structure,
It is a thermoplastic elastomer that has extremely strong physical crosslinks with high heat resistance and has excellent heat resistance and mechanical properties.
However, these hydroxy compounds are extremely insoluble in various solvents and other copolymerizable monomers, so when synthesizing polyesters using these hydroxy compounds, the polymerization temperature is kept at 300 to maintain the polymerization system in a uniform state. ℃
Since a high temperature close to or higher than that is required, the polymer produced by polycondensation is decomposed by heat, and it is difficult to stably synthesize a high molecular weight polyester.

The present invention has been made in view of such circumstances, and an object of the present invention is a polyester having properties as a thermoplastic elastomer, excellent in heat resistance and mechanical properties, and excellent in moldability. The object is to provide a method capable of stably producing

(Means for Solving the Problems) The inventors of the present invention have conducted extensive studies on improvement of thermal stability during polymerization, and as a result, by using a hindered phenol antioxidant and a sulfur stabilizer in combination, polymerization stability was improved. The inventors have found that the properties are significantly improved and have completed the present invention.

That is, the method for producing a polyester of the present invention comprises an aliphatic dicarboxylic acid represented by the following formula [I], an aliphatic diol, and a dihydroxy compound represented by the following formula [II] ] In the production of an aliphatic polyester having at least one of the monohydroxy compounds represented by the formula above, 0.001 to 5% by weight of a hindered phenolic antioxidant and 0.001 to It is characterized in that the monomer is polycondensed after adding 5% by weight of a sulfur-based stabilizer, thereby achieving the above object.

HOOC- (CH ₂₎ n-COOH (I) (wherein, n represents an integer of 0.) (In the formula, R ¹ and R ² independently represent an alkylene group, p is 3 or 4, and q and r are independently 0 or 1.) (In the formula, R ³ represents an alkylene group, 1 is 2 or 3, and
m is 0 or 1. In the above aliphatic dicarboxylic acid, if a dicarboxylic acid having more than 10 carbon atoms is used, the physical properties of the molded product obtained from the polyester are deteriorated. As the above dicarboxylic acid,
For example, oxalic acid, malonic acid, succinic acid, glutaric acid,
Adipic acid, suberic acid and sebacic acid are preferably used.

Examples of the aliphatic diol include glycol and polyalkylene oxide. Examples of the glycol include ethylene 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-
Examples thereof include diol, cyclohexane-1,3-diol, cyclohexane-1,4-diol, cyclohexane-1,4-dimethanol, etc. These may be used alone or in combination of two or more kinds. .

Examples of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyhexamethylene oxide and the like, and these may be used alone or in combination of two or more kinds. When the number average molecular weight of the polyalkylene oxide is small, the ability to impart flexibility to the resulting polyester decreases, and when it is too large, the physical properties such as thermal stability of the obtained polyester decrease.
It is preferably 20,000, more preferably 500 to 5,000.

The dihydroxy compound represented by the above formula [II] is a low molecular weight compound exhibiting liquid crystallinity, the alkylene groups R ¹ and R ² are preferably ethylene groups or propylene groups, q and r are 0 or 1, and 4,4 "-dihydroxy represented by the formula [A]
p-terphenyl, 4,4-dihydroxy-p-quaterphenyl represented by the following formula [B] and 4,4-di (2-hydroxyethoxy) -p-quaterphenyl represented by the following formula [C] Etc. are preferably used.

The transition temperature of 4,4 ″ -dihydroxy-p-terphenyl [A] from the crystalline state to the liquid crystal state is 260 ° C., and that of 4,4-dihydroxy-p-quarterphenyl [B] is 33 ° C.
6 ° C, that of 4,4-di (2-hydroxyethoxy) -p-quaterphenyl [C] is 403 ° C. The liquid crystal state means a state in which the compound is in a molten state and the molecules maintain the alignment state. The above dihydroxy compounds [II] may be used alone or in combination.

Liquid crystal molecules generally have high crystallinity, and as described above,
4,4 "-dihydroxy-p-terphenyl [A], 4,4
-Dihydroxy-p-quaterphenyl [B] and 4,
Since 4-di (2-hydroxyethoxy) -p-quaterphenyl [C] has a high transition point from its crystal to the liquid crystal state, when these dihydroxy compounds [II] are incorporated in the polymer chain, Polymers show unique properties.

That is, the dihydroxy compound [II] exhibits crystallinity,
Moreover, because of its high transition point, dihydroxy compounds [I
Even when the compounding amount of I] is small, a strong and heat-resistant physical crosslink is formed. As a result, it is presumed that a thermoplastic elastomer having high heat resistance can be obtained without impairing the flexibility derived from the soft segment.

The monohydroxy compound represented by the above formula [III] is a rigid low molecular weight compound having a paraphenylene skeleton, and the melting point of these compounds is extremely high, reflecting the characteristic molecular structure. Furthermore, the paraphenylene skeleton is known to be effective as a mesogen for low-molecular liquid crystal compounds, and it has a strong cohesive force not only in the solid state but also in the high temperature state (molten state). Is shown. Therefore, when the above-mentioned monohydroxy compound [III] is incorporated into the polymer terminal, it results in very strong physical crosslinks with high heat resistance, and a thermoplastic elastomer excellent in heat resistance is produced.

In the monohydroxy compound represented by the above formula [III], R ³ is preferably an ethylene group or a propylene group,
m is 0 or 1. Examples of the monohydroxy compound include 4-hydroxy-p-terphenyl, 4-hydroxy-p-quaterphenyl, 4- (2-hydroxyethoxy) -p-terphenyl, 4- (2-hydroxyethoxy)- p-quaterphenyl and the like can be mentioned.
The monohydroxy compounds [III] may be used alone or in combination.

Polyester comprising at least one of the above-mentioned aliphatic dicarboxylic acid [I], aliphatic diol and dihydroxy compound [II], and monohydroxy compound [III], a poly-silicone having two hydroxyl groups, a lactone, Aromatic hydroxycarboxylic acid may be contained as a constituent component.

The above-mentioned poly-silicone has two hydroxyl groups, and a poly-silicone having two hydroxyl groups at the molecular ends is preferable. For example, dimethyl polysiloxane, diethyl polysiloxane having two hydroxyl groups at both ends of the molecule, Examples thereof include diphenylpolysiloxane. The lower the number average molecular weight of the polysilicone, the lower the ability to impart flexibility to the resulting polyester, and the higher it becomes.
Since it becomes difficult to form polyester, 100 to 20,000 is preferable, and 500 to 5,000 is more preferable.

The lactone is a compound that opens a ring and reacts with an acid and a hydroxyl group to add an aliphatic chain, which imparts flexibility to the polyester, and which has 4 or more carbon atoms in the ring. It is preferably a 5-membered to 8-membered ring, and examples thereof include ε-caprolactone, δ-valerolactone, γ-butyrolactone and the like.

The aromatic hydroxycarboxylic acid imparts rigidity and liquid crystallinity to the polyester, and includes salicylic acid, metahydroxybenzoic acid, parahydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 3-bromo-4-hydroxyl. Benzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3-
Methyl-4-hydroxybenzoic acid, 3-phenyl-4-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 4-
Examples thereof include hydroxy-4′-carboxybiphenyl, and preferred are parahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, and 4-hydroxy-4′-carboxybiphenyl.

Furthermore, in order to improve the mechanical properties of the polyester, the dihydroxy compound [II]
Other aromatic diols and aromatic dicarboxylic acids may be contained as constituents.

Examples of the aromatic diol include hydroquinone, resorcin, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′- Dihydroxydiphenyl sulfide, 4,4 '
-Dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, bisphenol A, 1,1-di (4-hydroxyphenyl) cyclohexane, 1,2-bis (4-hydroxyphenoxy) ethane, Examples thereof include 1,4-dihydroxynaphthalene and 2,6-dihydroxynaphthalene.

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

In the polyester composed of the dihydroxy compound [II], the aliphatic diol and the aliphatic dicarboxylic acid, when the content of the dihydroxy compound [II] is low, the heat resistance is low, and when it is high, the elastic modulus is high and the flexibility is low. Since it becomes unsuitable as a thermoplastic elastomer, the content of the dihydroxy compound [II] is preferably 0.1 to 30 mol% in all monomers constituting the polyester, more preferably 0.5 to 20 mol%, More preferably 1.0-
10 mol%. In addition, when using polyalkylene oxide or polysilicone as diol other than aromatic,
The constitutional unit is counted as one monomer. That is, the degree of polymerization
Ten polyethylene oxide counts as zero monomer.

Further, a polyester composed of the above monohydroxy compound [III], an aliphatic diol and an aliphatic dicarboxylic acid is
When the content of the monohydroxy compound [III] decreases, the heat resistance decreases, and when the content of the monohydroxy compound [III] decreases, the molecular weight of the polyester does not increase sufficiently, resulting in poor physical properties. It is preferably set to mol%. The polyester composed of the dihydroxy compound [II], the monohydroxy compound [III], the aliphatic diol and the aliphatic dicarboxylic acid has a content of the hydroxy compound including the dihydroxy compound [II] and the monohydroxy compound [III]. When the amount is small, the heat resistance is lowered, and when it is large, the flexibility is not lowered and a sufficient increase in the molecular weight cannot be obtained. In this case, the ratio of the dihydroxy compound [II] and the monohydroxy compound [III] is preferably in the range satisfying 0 <[III] / [II] + [III] <2/3.

The polyester composed of the above constituents can be produced by any of the following generally known polycondensation methods.

A method in which a dicarboxylic acid and a diol component (including an aliphatic diol, a dihydroxy compound, a monohydroxy compound, etc.) are directly reacted.

A method of reacting a lower ester of dicarboxylic acid and a diol component by transesterification.

A method of reacting a dicarboxylic acid halide and a diol component in a suitable solvent such as pyridine.

A method of reacting a metal alcoholate of a diol component with a dicarboxylic acid halide.

A method of reacting an acetylated diol component and a dicarboxylic acid by transesterification.

In the polycondensation, a catalyst generally used in producing polyester may be used. As this catalyst, lithium, sodium, potassium, cesium, magnesium, calcium, barium, strontium,
Metals such as zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium, boron, cadmium and manganese, their organometallic compounds,
Examples thereof include organic acid salts, metal alkoxides, metal oxides and the like.

Particularly preferred catalysts are calcium acetate, diacyl stannous, tetraacyl stannic acid, dibutyltin oxide, dibutyltin dilaurate, dibutyltin malate, tin dioctanoate, tin tetraacetate, triisobutylaluminum, tetrabutyltitanate, germanium dioxide, and tris. It is antimony oxide. Two or more of these catalysts may be used in combination. In addition, water, alcohol, glycol, etc., which are by-products of polymerization, are efficiently distilled off,
In order to obtain a high molecular weight polymer, the reaction system is
It is preferable to reduce the pressure to 1 mmHg or less.

In addition, in the present invention, in order to improve the thermal stability during polymerization, both a hindered phenol antioxidant and a sulfur stabilizer are added before or during polycondensation.

Examples of the hindered phenolic antioxidant used in the present invention include triethylene glycol-bis [3-
(3-t-Butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-dibutyl-4-hydroxyphenyl) propionate], 2,4-bis -(N-octylthio) -6
-(4-Hydroxy-3,5-di-t-butylanilino)
-1,3,5-triazine, tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane, 2,2-thio-diethylenebis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2-thiobis (4-methyl-6-t -Butylphenol), N, N '
-Hexamethylenebis (3,5-di-t-butyl-4-hydroxy-4hydroxy-namamide), 3,5-di-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-hydroxybenzylphosphonate ethyl) calcium, tris- (3,5-di-
t-Butyl-4-hydroxybenzyl) -isocyanurate, 3,9-bis [2- (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy)
-1,1-Dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-
4-hydroxy-5-t-butylphenyl) butane, 2,2
-Bis [4- (2- (3,5-di-t-butyl-4-hydroxyhydrocinnamoyloxy)) ethoxyphenyl] propane, 2,6-di-t-butyl-4-methylphenol, 4, 4'-butylidene bis (3-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-
t-butylphenol) and the like.

Examples of the sulfur-based stabilizer include a pentaerythritol-based thioether compound represented by the general formula [IV] below and a 3,3′-thiodipropionate compound represented by the general formula [V] below.

(In the formula, R ⁴ , R ⁵ , R ⁶ , and R ⁷ independently represent an alkyl group having 1 to 36 carbon atoms.) (In the formula, R ⁸ and R ⁹ independently represent an alkyl group having 1 to 36 carbon atoms.) Specific examples of the pentaerythritol-based thioether compound [IV] include, for example, pentaerythritol tetrakis (3-butylthio). Propionate), pentaerythritol tetrakis (3-octylthiopropionate), pentaerythritol tetrakis (3-laurylthiopropionate), pentaerythritol tetrakis (3-stearyl thiopropionate) and the like. Specific examples of the 3,3'-thiodipropionate compound [V] include, for example, dimyristyl 3,3'-thiopropionate, dilauryl 3,3'-thiodipropionate and distearyl 3,3'-thio. Examples include dipropionate and ditridecyl 3,3 ′ thiodipropionate.

The amounts of the hindered phenol-based antioxidant and the sulfur-based stabilizer added are arbitrarily determined within the range of 0.001 to 5% by weight, and more preferably 0.01 to I% by weight, based on the total charged monomers. If the amount added is less than 0.001% by weight, the thermal stabilization efficiency during polymerization will decrease significantly,
On the other hand, if it exceeds 5% by weight, the polycondensation reaction rate decreases.

Thus, by using the hindered phenolic antioxidant and the sulfur stabilizer together, the polyester can be stably produced.

Further, the following additives may be added during or after the production of the aliphatic polyester within a range not impairing the practicality.
That is, glass fiber, carbon fiber, boron fiber, silicon carbide fiber, alumina fiber, amorphous fiber, inorganic fiber such as silicon / titanium / carbon fiber, organic fiber such as aramid fiber, calcium carbonate, titanium oxide, mica, talc. Inorganic fillers such as, hexabromocyclododecane, tris- (2,3-dichloropropyl) phosphate, flame retardants such as pentabromophenyl allyl ether, p-tert-butylphenyl salicylate, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2 '
-UV absorbers such as carboxybenzophenone and 2,4,5-trihydroxybutyrophenone, antioxidants such as butylhydroxyanisole, butylhydroxytoluene, distearylthiodipropionate and dilaurylthiodipropionate, N, N- Antistatic agents such as bis (hydroxyethyl) alkylamine, alkylallyl sulfonate, alkyl sulfanate, etc., inorganic substances such as barium sulfate, alumina, silicon oxide; higher fatty acid salts such as sodium stearate, barium stearate, sodium palmitate; Organic compounds such as benzyl alcohol and benzophenone, highly crystallized polyethylene terephthalate,
A crystallization accelerator such as polytrans-cyclohexanedimethanol terephthalate can be used.

Furthermore, the polyester obtained by the production method of the present invention is mixed with other thermoplastic resins such as polyolefin, modified polyolefin, polystyrene, polyamide, polycarbonate, polysulfone, polyester, etc., or mixed with a rubber component to obtain its properties. May be modified for use.

The polyester obtained by the production method of the present invention is formed into a molded product by press molding, extrusion molding, injection molding, blow molding or the like. The physical properties of the molded article can be arbitrarily changed depending on its constituent components, its compounding ratio and the like. When polyester is prepared as a thermoplastic elastomer, the molded product is preferably used for flexible molded products such as automobile parts, hoses, belts and packings, paints, adhesives and the like.

(Example) Below, this invention is demonstrated based on an Example.

Example 1 87.1 g (0.5 mol) of dimethyl adipate, 74.4 g (1.2 mol) of ethylene glycol and 4,4-dihydroxy-p
-Quaterphenyl (hereinafter referred to as DHQ) 16.7g (0.05m
ol) monomer mixture with antimony trioxide as catalyst
20 mg and 80 mg of calcium acetate with 3,9- as stabilizer
Bis [2- [3- (3-t-butyl-4-hydroxy-
5-Methylphenyl) propionyloxy] -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,
5] Undecane 90 mg (0.05% by weight based on all monomers)
And dilauryl 3,3'-thiodipropionate 90 mg (0.05% by weight based on the total monomers) were added, and the reaction system was placed under nitrogen to
The temperature was kept at 00 ° C for 2 hours to carry out a transesterification reaction. Next, this reaction system was heated to 320 ° C. in 30 minutes, kept at this pressure for 1 hour under normal pressure, and then subjected to polycondensation reaction for 2 hours under reduced pressure of 1 mmHg or less.

In order to evaluate the thermal stability of the obtained aliphatic polyester during polymerization, the color of the obtained aliphatic polyester was visually observed and the intrinsic viscosity was measured. The intrinsic viscosity [η] was measured in orthochlorophenol at 30 ℃. The results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 4 Aliphatic polyesters were obtained in the same manner as in Example 1 except that the types and / or amounts of stabilizers were as shown in Table 1. Observation of the color of the obtained polyester and measurement of the intrinsic viscosity were performed in the same manner as in Example 1. The results are shown in Table 1.
Shown in

Constituents DMA: dimethyl adipate EG: ethylene glycol DHQ: 4,4-dihydroxy-p-quaterphenyl Stabilizer A: 3,9-bis [2-3- (3-t-butyl-4-hydroxy5-methyl) (Phenyl) propionyloxy} -1,1
-Dimethylethyl] 2,4,8,10-tetraoxaspiro [5,
5] Undecane B: 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzylbenzene X: dilauryl 3,3'-thiodipropionate Y: pentaerythritol tetrakis (3-lauryl thiopropionate) From Table 1, the following was confirmed. Aliphatic polyesters prepared by using 0.01 to 5% by weight of a hindered phenol antioxidant and a sulfur stabilizer as stabilizers (Examples 1 to 4) have no or little coloration. It had the desired intrinsic viscosity. The aliphatic polyester produced by using either one of the above stabilizers (Comparative Examples 2 and 3) or neither (Comparative Example 1) was found to be greatly colored, and the intrinsic viscosity was The polymer is degraded. Further, the aliphatic polyester (Comparative Example 4) produced by using a large amount of the hindered phenolic antioxidant as a stabilizer (Comparative Example 4) did not have the desired intrinsic viscosity although no coloration was observed.

(Effect of the invention) The present invention uses a hindered phenolic antioxidant and a sulfur stabilizer together in the production of a polyester containing a hydroxy compound that is soluble at 300 ° C. or higher. A polyester can be stably obtained even at a high polycondensation temperature of not less than ° C.

The polyester thus obtained has a segment having a high crystallinity and a high melting point, such as a dihydroxy compound or a monohydroxy compound, which is introduced into a polyester mainly composed of an aliphatic dicarboxylic acid and an aliphatic diol. It has the performance as a thermoplastic elastomer and has excellent heat resistance, mechanical properties, and moldability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Niki 2-2 Hyakusan, Shimamoto-cho, Mishima-gun, Osaka (72) Inventor Torasuke Saito 5-17-21 Yamatedai, Ibaraki-shi, Osaka (72) Inventor Hiroki Kadomachi 7-20 Otemachi, Ibaraki-shi, Osaka (72) Inventor Daishiro Kishimoto 2-11-20 Mishimaoka, Ibaraki-shi, Osaka Umeyama Mansion 102 (56) Reference Soviet patent invention 186124 (SU) , A) Plastic, 38 [9] (1987) P. 14

Claims (1)

(57) [Claims] 1. An aliphatic dicarboxylic acid having a general formula represented by the following formula [I], an aliphatic diol, and a general formula having the following formula [II]:
In producing a polyester having at least one of a dihydroxy compound represented by the formula [1] and a monohydroxy compound represented by the following formula [III], 0.001 to 5% by weight of a hindered phenol based on all monomers charged. A method for producing a polyester, which comprises adding 0.001 to 5% by weight of a sulfur-based stabilizer and then polycondensing the monomer. HOOC- (CH ₂₎ n-COOH (I) (wherein, n represents an integer of 0.) (In the formula, R ¹ and R ² independently represent an alkylene group, and p is 3
Or 4, and q and r are independently 0 or 1. ) (In the formula, R ³ represents an alkylene group, 1 is 2 or 3, and m is 0 or 1.)