JPH04222825A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain a polyester, having properties as a thermoplastic elastomer and a high polymerization degree, excellent in mechanical properties and thermal stability in molding and suitable as automotive parts, hoses, coatings, etc. CONSTITUTION:(A) An aliphatic dicarboxylic acid (e.g. oxalic acid) expressed by formula I (n is 0-10), (B) an aliphatic diol (e.g. ethylene glycol or polyethylene oxide) and (C) a dihydroxy compound (e.g. 4,4''-dihydroxy-p-terphenyl) expressed by formula II (R<1> and R<2> are alkylene; p is 3 or 4; q and r are 0 or >=1) and/or a monohydroxy compound expressed by formula III (R<3> is alkylene; 1 is 2 or 3; m is 0 or >=1) are subjected to melt or solution polymerization and the resultant polymer is further polymerized in the solid phase.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyester, which has properties as a thermoplastic elastomer, has a high degree of polymerization, has excellent mechanical properties, and has excellent thermal stability during molding.

0002

2. Description of the Related Art Thermoplastic elastomers exhibit rubber elasticity at room temperature and can be molded, so they are widely used in various industrial products. In particular, polyesters containing dihydroxy or monohydroxy compounds having p-terphenyl or p-quarterphenyl skeletons,
The transition point (melting point) of this hydroxy compound from a crystalline state to a liquid crystal state is extremely high, reflecting its unique molecular structure, so it has extremely strong and heat-resistant physical crosslinks, and has excellent heat resistance and mechanical properties. A thermoplastic elastomer with excellent physical properties can be obtained, and the applicant has already filed an invention regarding this polyester (for example, Japanese Patent Application No. 1-23537).
No. 4, Patent Application No. 1-263476).

By the way, in order to produce such a high degree of polymerization polyester with excellent mechanical properties, as shown in Japanese Patent Application No. 1-235374, lower esters of dicarboxylic acids and aliphatic diols have been mixed with hydroxyl. The transesterification reaction is carried out at a temperature at which the compound does not melt, and after the transesterification reaction is completed, the reaction temperature is raised to dissolve the hydroxyl compound, and then the temperature is lowered to a temperature within a range where the hydroxyl compound does not precipitate. A further transesterification reaction was carried out at the same temperature, followed by polycondensation.

0004

However, in the above method, a long time is required for the polycondensation reaction in order to obtain a polyester with a high degree of polymerization. As the polycondensation time becomes longer, structural defects such as an increase in terminal carboxylic acids occur, so
This had the disadvantage of having an adverse effect on thermal stability during molding. As described above, although polyesters with a high degree of polymerization can be obtained by conventional methods, the problem remains that the thermal stability during molding is poor.

The present invention was made to solve the above-mentioned drawbacks, and its purpose is to have properties as a thermoplastic elastomer, have a high degree of polymerization, excellent mechanical properties, and have low heat resistance during molding. An object of the present invention is to provide a method for producing polyester having excellent stability.

[0006]

[Means for Solving the Problems] The method for producing a polyester of the present invention provides an aliphatic dicarboxylic acid whose general formula is represented by the following formula [I], an aliphatic diol whose general formula is represented by the following formula [I]
Dihydroxy compound represented by I] and the following formula [III]
In producing a polyester containing at least one of the monohydroxy compounds as a main component, the polymer is obtained by melt polymerization or solution polymerization, and then the polymer is subjected to solid phase polymerization. The above objective is achieved.

HOOC-(CH2)n-COOH
[I] (In the formula, n represents an integer from 0 to 10.)

[0008]

[Chemical formula 1]

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

0010

[Case 2]

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

If a dicarboxylic acid having more than 10 carbon atoms is used among the aliphatic dicarboxylic acids mentioned above, the physical properties of the molded article obtained from the polyester will deteriorate. Examples of the dicarboxylic acids include oxalic acid, malonic acid, succinic acid,
Glutaric acid, adipic acid, suberic acid and sebacic acid are preferably used.

[0013] Examples of the aliphatic diols include glycols and polyalkylene oxides. Examples of the above glycol include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol. Diol, 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-
Examples include dimethanol, which may be used alone or in combination of two or more.

[0014] 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. The number average molecular weight of the polyalkylene oxide is 100 to 20,000, because if it becomes small, the ability to impart flexibility to the polyester produced will decrease, and if it becomes too large, the physical properties such as thermal stability of the polyester obtained will decrease. is preferable, and more preferably 500 to 5,000.

The dihydroxy compound represented by the above formula [II] is a low-molecular compound exhibiting liquid crystallinity, and the alkylene groups R1 and R2 are preferably an ethylene group or a propylene group, and q and r are preferably 0 or 1. 4,4''-
Dihydroxy-p-terphenyl, 4,4'''-dihydroxy-p-quarterphenyl, 4,4'''-di(2-hydroxyethoxy)-p-quarterphenyl, and the like are preferably used.

The transition temperature of 4,4''-dihydroxy-p-terphenyl from the crystalline state to the liquid crystalline state is 260°C.
and that of 4,4'''-dihydroxy-p-quarterphenyl is 336 °C, and that of 4,4'''-di(2
-hydroxyethoxy)-p-quarterphenyl is 403°C. Note that the liquid crystal state refers to a state in which the compound is in a molten state and the molecules maintain an oriented state. Each of the above dihydroxy compounds [II] may be used alone or in combination.

Liquid crystal molecules generally have high crystallinity, and as mentioned above, 4,4''-dihydroxy-p-terphenyl, 4,4''-dihydroxy-p-quarterphenyl and 4,4'''-di(2-hydroxyethoxy)
-p-Quarterphenyl etc. have a high transition point from crystal to liquid crystal state, so these dihydroxy compounds [
II] is incorporated into a polymer chain, the polymer exhibits unique properties. That is, since the dihydroxy compound [II] exhibits crystallinity and has a high transition point, a strong and highly heat-resistant physical crosslink is formed even when the amount of the dihydroxy compound [II] is small. 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 represented by the above formula [III] are rigid, low-molecular compounds having a paraphenylene skeleton, and the melting points of these compounds are extremely high reflecting their characteristic molecular structure. 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 monohydroxy compound [III] is incorporated at the polymer end,
This results in extremely strong and heat-resistant physical crosslinking, producing a thermoplastic elastomer with excellent heat resistance.

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

[0020] A polyester made of at least one of the above aliphatic dicarboxylic acid [I], an aliphatic diol, a dihydroxy compound [II], and a monohydroxy compound [III], a polysilicone having two hydroxyl groups, or a lactone. Alternatively, aromatic hydroxycarboxylic acid may be contained as a constituent component.

The above-mentioned polysilicone has two hydroxyl groups, preferably polysilicone with two hydroxyl groups at the ends of the molecule, such as dimethyl polysiloxane and diethyl polysiloxane, which have two hydroxyl groups at both ends of the molecule. Examples include polysiloxane and diphenylpolysiloxane. When the number average molecular weight of polysilicone becomes small, the ability to impart flexibility to the polyester produced decreases, and when it becomes large, it becomes difficult to produce polyester, so the number average molecular weight is 10.
0 to 20,000 is preferable, more preferably 500 to
5,000.

[0022] 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 has four or more carbon atoms in the ring. It is preferable to have a 5- to 8-membered ring, and examples thereof include ε-caprolactone, δ-valerolactone, and γ-butyrolactone.

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.

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

Examples of the aromatic diol include hydroquinone, resorcinol, 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)
Examples include ethane, 1,4-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and the like.

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

[0027] In the polyester made of the dihydroxy compound [II], an aliphatic diol, and an aliphatic dicarboxylic acid, when the content of the dihydroxy compound [II] decreases, the heat resistance decreases, and when the content increases, the elastic modulus increases and the flexibility decreases. The content of the dihydroxy compound [II] is preferably 0.1 to 30 mol%, more preferably 0.5% by mole based on the total monomers constituting the polyester. 20 mol%, 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 degree of polymerization of 10 is counted as 10 monomers.

[0028] Furthermore, the above monohydroxy compound [III
], aliphatic diol, and aliphatic dicarboxylic acid, when the content of monohydroxy compound [III] decreases, the heat resistance decreases, and when the content increases, the molecular weight of the polyester does not increase sufficiently, resulting in poor physical properties. 0.1 of all monomers constituting polyester
It is preferable to set it as 20 mol%.

[0029] Further, the above polyester consisting of dihydroxy compound [II], monohydroxy compound [III], aliphatic diol and aliphatic dicarboxylic acid is a hydroxy compound which is a combination of dihydroxy compound [II] and monohydroxy compound [III]. If the content is too low, the heat resistance will be decreased, and if it is too high, the flexibility will be decreased and a sufficient increase in molecular weight will not be obtained. At this time, the ratio of dihydroxy compound [II] and monohydroxy compound [III] is 0<[III]/[II]+
A range satisfying [III]<2/3 is preferable.

[0030] In order to produce a polyester consisting of the above-mentioned components, a polymer is first obtained by melt polymerization or solution polymerization. Examples of melt polymerization or solution polymerization include: (1) direct reaction of dicarboxylic acid and a diol component (including aliphatic diols, dihydroxy compounds, monohydroxy compounds, etc.), (2) method of directly reacting dicarboxylic acid with diol component, and (2) method of directly reacting dicarboxylic acid with diol component. (1) A method in which a dicarboxylic acid halide and a diol component are reacted in a suitable solvent such as pyridine, (2) A method in which a metal alcoholate of a diol component is reacted with a dicarboxylic acid halide. , (2) A method in which an acetylated diol component and a dicarboxylic acid are reacted using transesterification.

When using the method (2) above, it is preferable to add the diol component, dicarboxylic acid or oxyacid to the reaction system before the reaction is completed. When using the method (2) above, it is preferable to add the lower ester of dicarboxylic acid or diol component to the reaction system before the transesterification reaction is completed. When using method (1) above, it is preferable to add a dicarboxylic acid halide or diol component to the reaction system. When using method (1) above, it is preferable to react the diol component in the form of a metal alcoholate, or to react the dicarboxylic acid in the form of a halide. When using the method (2) above, it is preferable to add the acetylated diol component or dicarboxylic acid before the end of the transesterification reaction.

[0032] In melt polymerization or solution polymerization, catalysts generally used in producing polyester may be used. This catalyst includes lithium, sodium,
Potassium, cesium, magnesium, calcium, barium, strontium, zinc, aluminum, titanium,
cobalt, germanium, tin, lead, antimony, arsenic,
Metals such as cerium, boron, cadmium, manganese,
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. Further, these may be added at any time before the start of polycondensation.

In melt polymerization and solution polymerization, there is no need to carry out long-term reactions (direct esterification reactions, transesterification reactions, and polycondensation reactions) at high temperatures, and the intrinsic viscosity [η]: 0.5 to 1.0 It is preferred to produce a polymer of Note that this intrinsic viscosity [η] is a value measured at 30° C. in orthochlorophenol. If it is smaller than this range, it will take a long time to obtain a sufficient high molecular weight in the subsequent solid phase polymerization, which is not preferable. In addition, if an attempt is made to obtain a polymer larger than this range, it is not appropriate because the number of terminal carboxylic acids will increase due to thermal deterioration of the polymer. Furthermore, in order to obtain a polymer with the desired intrinsic viscosity, it is necessary to efficiently distill off water, alcohol, glycol, etc. that are produced as by-products during polymerization.
It is preferable to reduce the pressure of the reaction system to 1 torr or less in the late stage of polymerization. The reaction temperature is generally 150-350°C. Next, the polymer obtained by melt polymerization or solution polymerization is subjected to solid phase polymerization. In this solid phase polymerization, it is preferable to form the polymer obtained by melt polymerization or solution polymerization into flakes or powder. To make the polymer into flakes or powder,
After the polymer has been cooled to below its softening point, it can be mechanically pulverized, and in this way a polyester having a sufficiently high molecular weight can be obtained. The reaction temperature during solid phase polymerization is preferably 150°C to 240°C. If it is lower than this range, polyester with a sufficient high molecular weight cannot be obtained,
If it is higher than this range, the thermal stability of the polyester during molding will deteriorate. The reaction time is preferably 5 to 24 hours; if it is shorter than this range, polyester with a sufficient high molecular weight cannot be obtained. Furthermore, if the length is longer than this range, it will not adversely affect the physical properties of the polyester, but production efficiency will decrease, which is not preferable. It is preferable that the pressure inside the reaction system be reduced to 0.1 torr or less, or that the atmosphere be replaced with nitrogen.

[0035] During the melt polymerization, solution polymerization or solid phase polymerization, various stabilizers such as hindered phenol antioxidants and phosphorus stabilizers may be used.

Examples of hindered phenolic antioxidants include triethylene glycol bis[3-(3-
t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3
-(3,5-dibutyl-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, 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, and the like. Examples of the above-mentioned phosphorus stabilizers include tris(nonylphenyl)phosphite, triisooctylphosphite, triisodecylphosphite, triphenylphosphite, diphenylisodecylphosphite, diphenylisooctylphosphite, phenylisodecyl Phosphite compounds such as phosphite, diisooctylphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite; distearylpentaerythritol-di-phosphite, dioctylpentaerythritol-di-phosphite, Diisodecylpentaerythritol-di-phosphite, bis(2
, 4-di-t-butylphenyl)pentaerythritol-di-phosphite, bis(2,6-di-t-butyl-
Pentaerythritol-di-phosphite compounds such as 4-methylphenyl)pentaerythritol-di-phosphite; examples include tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylenephosphonite. . Furthermore, the following additives may be added during or after the production of the polyester 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 polyester of the present invention can be used with other thermoplastic resins such as polyolefins, modified polyolefins, polystyrenes, polyamides, polycarbonates,
It may be used by mixing with polysulfone, polyester, etc., or by mixing with a rubber component to modify its properties.

The polyester of the present invention can be used as an elastomer with excellent heat resistance, and can be used in press molding,
It is made into a molded product by a melt molding method such as extrusion molding, injection molding, or blow molding. The physical properties of a molded product can be changed arbitrarily depending on its constituent components and their blending ratios, and are suitable for molded products that require flexibility and heat resistance such as automobile parts, hoses, belts, and packing, as well as paints, adhesives, etc. It can be suitably used for.

[0050]

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

Example 1 (A) Synthesis of polyester 348.4 g (2.0 mol) of dimethyl adipate and ethylene glycol were placed in a 1 liter glass flask equipped with a stirrer, thermometer, gas inlet and distillation port. 290.0 g (5.0 mol), 4,4'''-dihydroxy-p-quarterphenyl (DHQ), 0.2 g of antimony oxide and 0.2 g of calcium acetate as a catalyst.
44 g, and 1,3,5-trimethyl- as a stabilizer.
0.4 g of 2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene and tris(2
,4-di-t-butylphenyl)phosphite 0.4
I prepared it. 200℃ after replacing the inside of the flask with nitrogen
The mixture was kept for 2.0 hours to carry out the transesterification reaction. During this reaction, methanol was distilled out from the reaction mixture. Then,
This reaction system was heated to 320° C. over 30 minutes, stirred for 30 minutes, then cooled to 300° C., the pressure was reduced to 1 torr or less, and the polycondensation reaction was carried out in this state for 1.5 hours. During the reaction, ethylene glycol was distilled out, and an extremely viscous liquid was formed in the flask. The product was then cooled to solidify and then ground. The polymer powder was placed in a vacuum dryer, and solid phase polymerization was performed at 200° C. under reduced pressure of 0.1 torr or less for 20 hours.

Thereafter, the intrinsic viscosity of the obtained polymer was measured. The intrinsic viscosity [η] was measured in orthochlorophenol at 30°C. In addition, in order to evaluate the thermal stability during molding, this polymer was dried at 100°C for 5 hours, and then tested in a Shimadzu flow tester CFT-500 at 240°C for 3 hours.
After staying for 0 minutes, the sample was taken out and its intrinsic viscosity [η] was measured (test load: 100 kg, die diameter: 1 mm, die length: 10 mm). These results are shown in Table 1.

[0053] Also, the obtained polymer was subjected to an injection pressure of 1500
Kg/cm2, mold temperature 70℃, cylinder temperature 220℃
A 2mm thick flat plate was made by injection molding.
Next, a No. 3 dumbbell test piece was punched out in accordance with JIS K-6301. The tensile strength and elongation at break of this dumbbell test piece were measured at a tensile speed of 50 mm/min.
, room temperature, and 100°C, respectively. These results are shown in Table 2.

Comparative Example 1 Melt polymerization was carried out in the same manner as in Example 1, but solid phase polymerization was not carried out. Each physical property of the obtained polymer was measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

Comparative Example 2 Melt polymerization was carried out in the same manner as in Example 1, except that the polycondensation reaction was carried out for 3.5 hours in order to obtain a polymer with a high degree of polymerization by the conventional method, and solid phase polymerization was not carried out. There wasn't. Each physical property of the obtained polymer was measured in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

According to the present invention, during melt polymerization or solution polymerization, a direct esterification reaction and/or transesterification reaction followed by a polycondensation reaction are carried out. Since there is no need to hold the polyester at a low temperature, a polymer with few structural defects can be obtained, and by chain extension at a relatively low temperature in solid phase polymerization, a polyester having a sufficiently high molecular weight can be obtained without producing structural defects. Therefore, a polyester having a high degree of polymerization, excellent mechanical properties, and excellent thermal stability during molding can be obtained.

Claims (1)

[Claims] Claim 1: An aliphatic dicarboxylic acid, an aliphatic diol whose general formula is represented by the following formula [I], and an aliphatic diol whose general formula is represented by the following formula [I].
Dihydroxy compound represented by I] and the following formula [III]
In producing a polyester containing at least one of the monohydroxy compounds represented by the formula, a polyester is obtained by obtaining a polymer by melt polymerization or solution polymerization, and then subjecting the polymer to solid phase polymerization. Manufacturing method: HOOC-(CH2)n-COOH
[I] (In the formula, n represents an integer from 0 to 10.)
Formula 1] (wherein R1 and R2 independently represent an alkylene group, p
is 3 or 4, and q and r independently represent 0 or an integer of 1 or more. ) [In the formula, R3 represents an alkylene group, l is 2 or 3, and m represents an integer of 0 or 1 or more.