JPH021732A - Production of polyester - Google Patents

Abstract

PURPOSE:To obtain the subject polymer suitable as molding materials, films, etc., with hardly any coloring by adding a hydroxycarboxylic acid, etc., to a diol and dicarboxylic acid, acetylating the resultant mixture, distilling off acetic anhydride at a low temperature and polymerizing the mixture. CONSTITUTION:(A) A diol expressed by formula I (R<1> is aromatic group), such as hydroquinone, and (B) a dicarboxylic acid expressed by formula II (R<2> is aromatic group), such as terephthalic acid, are blended with (C) a hydroxycarboxylic acid expressed by formula III (R<3> is aromatic group), such as p-hydroxybenzoic acid, or further (D) an oligoester, containing terephthalic acid and ethylene glycol as constituent units and expressed by formula IV (R<4> is 6-20C aromatic group, etc.; R<5> is 2-40C aliphatic group, etc.). (E) Acetic anhydride is then added and reacted therewith. Acetic anhydride and acetic acid are subsequently distilled out of the system to carry out melt polymerization and afford the objective polymer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing polyester.

Specifically, the present invention relates to a method for producing polyester, which has a low degree of coloring, has a good appearance, can be colored into a desired color by adding a coloring agent, etc., and can be commercialized as a molding material, film, or fiber.

[Conventional technology]

Methods for producing polyester containing an aromatic oquine compound include melt polymerization, solution polymerization, interfacial polymerization, etc., but melt polymerization is generally used due to its production cost and process simplicity.

The melt polymerization method is generally classified into the following three methods.

(a) A method using a compound whose OH group has been afurated in advance.

(b) A method in which a hydroquine compound is used as a raw material and an unlying agent is added in the reaction system. Acetic anhydride is usually used as the affluating agent.

(c) A method using an arylcarboxylate compound in which the C0OH group is a COOAr group (representing an Ar neararyl group) which has been aryl esterified in advance.

[Problems to be solved by the present invention]

The above methods (a) and (c) are excellent in producing polyester that is stable and has little coloring, but on the other hand, (a)
Disadvantages such as high cost of raw material compounds and (b) slow polymerization rate.

On the other hand, in method (b), the raw material compound is generally cheap;
It has the advantage that the polymerization rate is generally faster than that of methods (a) and e→, but on the other hand, polymers produced by method (b) tend to be colored brown, making them unusable in some cases. This is presumed to be because when excess acetic anhydride is present at a high temperature exceeding 2 (10'C), side reactions such as Friedel-Krach reaction and aldol condensation occur.

[Means for solving problems]

In view of the above points, we have conducted extensive studies and found that it is possible to produce polyester with a low degree of coloration by distilling substantially excess acetic anhydride out of the system at low temperatures. invention has been achieved.

That is, the present invention uses (1) at least a diol represented by the following general formula (1) and a dicarboxylic acid represented by the following general formula symbol), or (ii) a hydroxycarboxylic acid represented at least by the following general formula (In). or ii) using at least the above hydroxycarboxylic acid and an oligoester or polyester having a structural unit represented by the following general formula (5), acetylation with acetic anhydride in the system, followed by melt polymerization. In producing polyester, after acetylation is carried out at 270°C or lower, excess acetic anhydride and acetic acid are substantially distilled out of the system at 211°C or lower, and then melt polymerization is carried out. Production method.

HO-R"-OH......(1) HO-R3-COH......Cl1l) (Here, (1), (It), (1) formula RI R2 and R3 are covalent aromatic hydrocarbon groups R11X R1
2 groups (wherein R'' and R12 are covalent aromatic hydrocarbon groups, and X represents an oxygen atom, sulfur atom, sulfonyl group, carbonyl group, hydrocarbon group, ester group, or direct bond). However, the hydrogen atom of the aromatic ring may be substituted with a halogen atom, a hydrocarbon group, an alkoxy group, or a fenoquine group. group hydrocarbon group, divalent alicyclic hydrocarbon group having 9 to 20 carbon atoms or/and carbon number/~0
represents a co-valent aliphatic hydrocarbon group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group), a rogene atom, or an alkyl or alkoxy group with a number of carbon atoms/~g), R5 is a divalent aliphatic hydrocarbon group having 2 to 110 carbon atoms, a divalent alicyclic hydrocarbon group having 1 to 20 carbon atoms, and a covalent aromatic group having 6 to 20 carbon atoms forming an aromatic ring. group hydrocarbon group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having carbon number/~q or an alkokene group), or a polyalkylene ogyne having a molecular weight of gO to gooo (indicating a doco-valent radical).

The present invention will be explained in more detail below.

As the hydrocarbon group for R'' and R12 mentioned above, an alkylene group or an alkylidene group is particularly preferable.

Specific examples of diols represented by the general formula <1) (hereinafter simply referred to as (1)) include no-hydroquinone, resorcinol, methylhydroquinone, t-butylhydroquinone, 1.2.5-di-t-butylhydroquinone ,/
, t, u-t') methylresorcin, chlorohydroquinone, nitrohydroquinone, dimethylaminohydroquinone, /, U-dihydroxy/naphthol, /, S-dihydroxynaphthol, hesi-6-cyhydroxynaphthol, core 6-cyhydroxynaphthol, Co, 7-hydroxynaphthol 1.2.2'-bis(cuhydroxyphenyl)propane, 2-'-bis(tI-hydroxy-
3,5-dimethylphenyl)propane 1.2.2'-bis(couhydroquine 3.s-dichlorophenyl)-furopane, J,, 2'-bis(p-hydroquino-3-methylphenyl)-propane 1.2. 2'-bis(2-hydroxy/-,,?-chlorophenyl)propane, bis(<=
-hydroxyphenyl)-methane, bis(q-hydroxy/-3-dimethylphenyl)-methane, bis(<=-
hydroxy/--3,S-dichlorophenyl)-methane, bis(hydro-hydroxy/-3,S-dibromophenyl)-
-methane, /, /-bis(couhydroquine)cyclohexane, p,Il'-dihydroxydiphenylbis(hiro-hydroxyphenyl)-ketone, bis(couhydroquine-3,s-dimethylphenyl)-ketone, bis(couhydroquine- , 7,5-dichlorophenyl)-ketone, bis(<=-hydroxyphenyl) sulfide,
Examples include, but are not limited to, bis(4t-hydroxy-3-chlorophenyl) sulfide, bis(cou-hydroxyphenyl) sulfone, bis(p-hydroxy-3 is monodichlorophenyl) ether, and the like. They may also be used as a mixture.

Many of these are easily oxidized, and when using them, it is preferable to remove oxygen and air from the reaction system.

Dicarboxylic acid represented by the general formula (■) (hereinafter simply (1)
). ) Specific examples of phthalic acid, isophthalic acid, naphthalene-, 2,6-dicarboxylic acid, naphthalene-/, 5-dicarboxylic acid, diphenyl-e4'-
Dicarboxylic acid, diphenyl,? ,,? '-dicarboxylic acid, methyl terephthalic acid, methyl isophthalic acid, diphenyl ether-1I, 'd'-dicarboxylic acid, diphenylthioether-y4'-dicarboxylic acid, diphenylsulfonoli, V'-dicarboxylic acid, diphenyl ketone-
Examples include aromatic dicarboxylic acids such as q,z'-dicarboxylic acid, 2-cyphenylpropane, ri'-dicarboxylic acid, but are not necessarily limited thereto. Further, these may be used in combination of one or more types. Specific examples of the hydroxycarboxylic acid represented by the general formula (1) (hereinafter simply referred to as (1)) include p-hydroxybenzoic acid, m -Hydroxybenzoic acid, 7-hydroxybenzoic acid, vanillic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, 7-hydroxybenzoic acid, 7-hydroxybenzoic acid, hydroxybenzoic acid, hydroxybenzoic acid, 7-hydroxybenzoic acid, , 6-difluoro-p-hydroxy-7benzoic acid, cohydroxo-6
-naphthoic acid, cohydroquinaphthoic acid, /-hydroquinaphthoic acid, etc., and these may be used in combination.

In order to produce a polyester or oligoester (hereinafter simply referred to as ■) having a structural unit represented by the general formula (■), a carboxylic acid HOOCR'C0OH represented by the general formula (g)... (A) (wherein R4 has the same meaning as in general formula (5)) and its esters are used, and examples of carboxylic acids include terephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid,
Fluoroterephthalic acid, chloroterephthalic acid, methylterephthalic acid, isophthalic acid, phthalic acid, methoxyinphthalic acid, diphenylmethane p,tI'-dicarboxylic acid,
diphenylmethane 3,3'-dicarboxylic acid, diphenyl ether<z4'-dicarboxylic acid, diphenyl-u,l
I'-dicarboxylic acid, naphthalene, etc. 6-dicarboxylic acid, naphthalene to S dicarboxylic acid, naphthalene/, hyorodicarboxylic acid, adipic acid, sebacic acid, azelaic acid, speric acid, dodecanedicarboxylic acid, 3-methyl azelaic acid, glital Examples include succinic acid, cyclohexane dicarboxylic acid, cyclohexane dicarboxylic acid, cyclopentane dicarboxylic acid, and cyclopentane dicarboxylic acid. These may be used as a mixture, and any of those represented by the general formula (g) can be used.

Also, the general formula (V) used to produce the general formula (V) is
Specific examples of the diol HOR50H represented by B) (B) (in the formula, R5 has the same meaning as in the general formula (■)) include ethylene glycol, /, 3-propanediol, /艷-propanediol, /, 3-butanediol, /, tI-butanediol, ;C opentyl glycol, /, A hexanediol, /112-dodecanediol, 7chlorohexa://,'ldiol, 7chlorohexane 83 Diol, /Chlohexane/, 2-Diol, Ncrobempe7
Examples include tan/, 3-diol, diethylene glycol, polyethylene glycol, hydroquinone, resorcinol, bisphenol A1 methylhydroquino/, chlorohydroquinone, co-, 6-naphthalene diol, but these may be used in combination. Generally, any compound represented by the general formula (B) can be used.

As the polyester or oligoester represented by the formula (IV) used in the present invention, any of those represented by the general formula (■) can be used, but polyethylene terephthalate, polybutylene terephthalate and Those oligomers are preferred, especially polyethylene terephthalate and its oligomers.

In order to produce the polyester of the present invention, these (1) to
One or more or two or more hydroquine carboxylic acid compounds (I) selected from (rV) can be used as raw materials.

In particular, it is preferable to use at least one (IV) as a raw material. Examples of this are (1), (If), and (I
There are combinations of (I) and (IV), combinations of (I) and (m), and combinations of (I) and (IV).

Also, a combination of only (1) and (II), (,1), (1),
Combinations of (m) and (1) combinations in which two or more types of a-a are used are also preferred.

When using the raw materials (1) to (IN), it is preferable to add the acetylating agent at the same time as the raw materials. In this case, 2'lO℃
It is preferable to carry out the following. When using (IV) as a raw material, an acetylating agent may be added at the same time as the raw material, but (1) and/or (II) and/or (I
II) and ([V) may be reacted in advance to produce a copolymerized oligomer, and then an acetylating agent may be added to carry out acetylation.

When producing a copolymerized oligomer of (1) and/or (It) and/or (1) and (IV), the reaction temperature is 200 to 330°C, preferably θ to 3θO0C, and the reaction time is S minutes to 70 hours, preferably 2
It can be carried out for a period of 0 minutes to 3 hours.

In this case, when using (1) which is easy to color, it is preferable not to use (1) in the production stage of the copolymerized oligomer, but to add (1) before the completion of the subsequent acetylation.

The reaction is carried out until the remaining amount of the oxycarboxylic acid compound is usually 70 mol or less, preferably 50 mol or less, based on the charge 1.Although the reaction can be carried out without a catalyst, if necessary, a catalyst can be used. It is carried out by adding.

Next, acetylation and post-acetylation techniques, which are the features of the present invention, will be explained.

Acetylation is carried out at a temperature of 5tIO°C or lower, preferably 100°C or lower, more preferably θ°C to igo'c, and most preferably so'C to 760'C.

If it exceeds 2'IO'Cf, a side reaction with acetic anhydride will occur, causing coloration, which is not preferable.

On the other hand, acetylation at low temperatures (less than 20° C.) is preferable in that it does not cause coloration, but is not preferable in that it slows down the polymerization rate.

Acetylation is preferably carried out under N2 seal or N270-, but may also be carried out under pressure. The reaction is carried out for 70 minutes to 10 hours, preferably 20 minutes to 3 hours.

When the mole deposit e of acetic anhydride, which is an acetylating agent, is used, and the moles of raw materials (1), (II), and (1!l) used are represented by a, b, and c, respectively, the following is preferable. Preferably, .

The number of moles of acetic anhydride used is In this case, the polymerization rate becomes slow, which is not preferable.

In the case of , the produced polymer is preferably colored and is good.

After acetylation, the temperature is raised to carry out polymerization at 20°C to 3so°C, but excess acetic anhydride and generated acetic acid are removed from the reaction system before the temperature is raised, or even after the temperature is raised, up to 0°C. is substantially distilled off.

Here, "substantially" means that the amount is less than the co-weight ratio in the reaction system, preferably less than 1% by weight, more preferably less than 0.8% by weight. Methods for forced distillation include (1) reducing the pressure, (ii) blowing inert gas into the entire reaction system, and (iii) azeotropically distilling it with other compounds. It is preferable to do so. in this case,
'I 00 m5Hf! It is preferable to reduce the pressure to below, particularly preferably below 1/00 rmHg.

However, in order to prevent unreacted upper particulate matter from being distilled out, the pressure should be kept above /IIIHg and the pressure should be kept below the boiling point or sublimation point of the acetylated raw material compound such as diacetate or acetoxy7carboxylic acid. It is important to set the temperature.

Here, leaving the excess acetic anhydride and the acetic acid produced, 2
If the temperature exceeds 10°C, it will turn brown, which is not preferable.

Specifically, after performing acetylation with acetic anhydride, the temperature at which the acetylation was performed is once / + mH,! i'
After reducing the pressure to ~/00 a+Hg and distilling off excess acetic anhydride and most of the acetic acid produced, the temperature is raised.
During this time as well, the temperature is raised while setting the pressure and temperature to be below the boiling point and sublimation point of the acetylated raw material compound such as diacetate and acetoxy7carboxylic acid. In other words, during this period, the pressure is normally /θOTTmHf/˜normal pressure.

By carrying out the reaction in this manner, excess acetic anhydride and acetic acid are substantially eliminated from the reaction system, and a polyester having a low degree of coloring can be obtained regardless of the subsequent polymerization conditions.

Incidentally, when the concentration exceeds 211 O'C'l, condensation begins, and it is natural that the acetic acid produced at that time is distilled off.

The polymerization is carried out at a temperature of 20°C to 3Sθ°C, preferably a cog θ°C to 3.0°C.
It is preferably carried out at 30°C, in which case the pressure is gradually reduced initially, and the temperature is preferably 7 A Of/ to 7 WnH? The time required to gradually reduce the pressure to 30 minutes or more, preferably AO minutes or more, especially /θ, H?
It is important to perform the depressurization gradually for 827 minutes.

The polymerization step may also be carried out without a catalyst, but it may be carried out in the presence of a catalyst if necessary.

〔Example〕

The present invention will be specifically illustrated by examples below, but the present invention is not limited thereto unless it departs from the gist thereof.

In addition, each measurement value in an Example was calculated|required as follows.

The method for quantifying acetic anhydride and acetic acid is to measure the reaction solution sampled at a predetermined temperature approximately/L? Collect and add chloroform to 2
After stirring well/standing for day and night, gas chromatography (measurement conditions: PEG-+20M, j%u
monchromosorbw (DMC8) 'θ/
gθmesh) was used to detect and quantify acetic acid.

It is thought that the acetic anhydride in the reaction system is involved in coloring, so it is actually preferable to quantify the amount of acetic anhydride in the reaction system, but due to the analytical method, the amount of acetic anhydride remaining in the system and the amount of acetic acid are The combined amount was quantified.

What is the value of ηinh (intrinsic viscosity) for O, S in a mixture of phenol and tetrachloroethane =/:/ (weight ratio)? 7dl
Measured at 30°C. The final product ηinh is 0.3d
Ill? The above is preferably o, 3sdt 77 or more.

In addition, a capillary rheometer is used to measure melt viscosity.
(manufactured by Intesco), the temperature was 320°C, the shear rate (?')/005ec-', and the length/diameter of the cylinder nozzle was 30.

The hue was determined by determining the L value using a color difference meter manufactured by Nippon Heavy Industries, Ltd., and was used as a guideline.

Example/ A glass tube equipped with a stirring blade, a nitrogen inlet, and a decompression port,
p-Hydroxybenzoic acid! ; i, ir y (o, 3S mol) and polyethylene terephthalate oligomer (η
1nh=0.09gdll? )? 2. / S''
, 0. ．． 37 S mol), and after performing vacuum displacement, placed under a N2 stream and immersed in an oil bath at 2'10°C.
- Allowed to react for hours.

Next, the temperature was lowered to 7'10°C, and 7 g of acetic anhydride was added.
(o, 375 mol) was added dropwise over 3θ minutes, and then
Stirring was continued for 0 minutes to allow acetylation. Thereafter, the excess acetic anhydride present in the system is distilled out by reducing the pressure to λOfi Hg at 0°C, and the acetic acid produced at the same time is also distilled out (sampling is carried out here). ), the temperature was raised to 300 wnHl and the temperature was started to increase. /
The temperature was raised to 2'lO<0>C over a period of approximately 5 hours, while sampling was taken at time point (2) at 0°C and time point (2) at 2EC°C.

(Sampling is also carried out at this point■.) After that, the pressure is reduced while increasing the temperature, the core is brought to 5℃ in 1 hour, and then 27'
! The polymerization was made to 0.3 H.9 over 7 hours at i.degree. C., and polymerization was continued in this state for an additional hour to complete the polymerization.

The polymer thus obtained is η1nh=0.72
It was p, L=7g, and 0.

The total amount of acetic anhydride and acetic acid at each time point of ■, ■, ■, ■ is /, /, 2% by weight, o6g of the entire reaction solution, respectively.
o Weight, 0.799% by weight 0. ! ; It was 7% by weight.

Comparative Example 1 The steps up to acetylation were carried out in the same manner as in Example. After that, the temperature was raised to 275°C over 2.5 hours at normal pressure without reducing the pressure, and then the pressure was reduced.

During that time, immediately before the end of acetylation, the temperature rises to 70°C (■), -00°C (■), and the temperature rises to (70°C) ■.
sampled at. 0 in about 2 hours after starting decompression
．． ltttmHji, and the polymerization was completed over an additional 9 hours.

The polymer thus obtained has ηinh =0.6
3, and L=sg,s.

The total amounts of acetic anhydride and acetic acid at each time point of ■, ■, ■, and ■ are 15.7% by weight and 9% by weight of the entire reaction solution, respectively.
, y, 2% by weight, and 2.9% by weight.

Example Co p-hydroxy 7 benzoin reed gg, 3 g, polyethylene terephthalate oligomer fJO0') 9° acetic anhydride 4
Example 1 was carried out in the same manner as in Example 1 except that 3 and 31 were changed.
Sampling was also conducted at the same location.

The resulting f' polymer has ηinh = 0.9
! ; 6, and L=49. ! ;Met.

The total abundance ratio of acetic anhydride and acetic acid at each point of ■, ■, ■, ■ is 7.2q weight percent, θJ 3 weight%,
o,'yg% by weight, the ratio was 0.7/weight.

Comparative Example - The amount of raw materials used was the same as in Example -, and the process was carried out in the same manner as in Comparative Example.

The resulting polymer has ηinh = 0.9
'I 7 and L,=,75. It was

The total abundance ratios of acetic anhydride and acetic acid at each time point of ■, ■, ■, and ■ are 3% by weight, 3% by weight, and 0% by weight, respectively. % by weight, 5.7% by weight, and 3.6% by weight.

Example 3 For p-hydroxy-7-ben, the amounts of folic acid and polyethylene terephthalate oligomer used were the same as in Example/, and the amount of
After carrying out the reaction at C for several hours, the temperature was lowered to 790°C, and after adding hydroquinone fg, 3j7, acetic anhydride'z
! ;09 was added, and the rest was carried out as in Example/.

The polymer obtained in this way has η1nh=0.6q
and L=7. ,? , it was.

The total amount of acetic anhydride and acetic acid at the points of ■, ■, ■, and ■ is 1.03% by weight of the entire reaction solution, θ0g3% by weight,
They were 0.72% by weight and 0.63% by weight.

Comparative Example 3 The raw materials and the amounts used were the same as in Example 3, and the process was carried out in the same manner as in Comparative Example.

The resulting polymer has η1nh=0. b It was 2 and 1 = uJ7.

The total amounts of acetic anhydride and acetic acid at each time point of (1), (2), (2), and (2) are 76.7% by weight of the entire reaction solution, respectively, and 9. The gM children's care was 3% by weight and 3.0% by weight.

Example: In a glass polymerization tube equipped with a stirring blade, a nitrogen inlet pipe, and a pressure reduction port, add 6JS g of bisphenol A, 2 Jqg of terephthalic acid, 2 Jqg of isophthalic acid, 9.9 q of acetic anhydride, and 3. sj! After reacting for 7 hours at it, to'C/lI
At O℃! ; Depressurize with OyamH91 and leave there for 30 minutes!
The reaction was carried out using OrmH9, and most of the acetic anhydride and acetic acid were distilled out. I did a sampling here■. then 3
The pressure was returned to 00rttmH9, and the temperature was raised to 2LttO℃ over 5 hours, during which time the pressure was increased to 2LttO℃, 20(
Sampling was done at 7'C and 2110'C. (
Let them be ■, ■, and ■, respectively. )2q0°C, 300mmH
After reacting at F for 7 hours, the temperature was raised to 30θ°C over 7 hours.

Thereafter, the pressure was reduced at 300°C to carry out polymerization. 300
After 7 hours from the time when the temperature reached 0.3°C, the final concentration of HE was 0.3 mm, and the polymerization was completed.

The generated polymer is η1nh=θj g, and L2g
It was O.

The total amounts of acetic anhydride and acetic acid at each time point of ■, ■, ■, ■ are respectively 0.9f weight range, θ, g g weight width, 0,12
% by weight, 0.33% by weight.

Comparative Example Using the same raw materials and the same amounts as in Example 1, acetylation was carried out at 1IO℃ for 7 hours, and then the temperature was raised to 30% over 365 hours.
The temperature was 0°C. During / '& 0℃, / 700C, 2
Sampling was carried out at 000C and 0C. (Respectively: ■, ■, ■, ■.) From the point when the temperature reaches 300℃, 7
The polymerization was completed at a final temperature of 0.3° C. mH1.

The generated polymer is y7inh = 0. ! ;? and
L=<4L.

The total amount of acetic anhydride and acetic acid at each time point of ■, ■, ■, and ■ is 20. weight%, 10.3 weight ratio, 5.5 weight ratio, 3. /It was the weight clerk.

Example! z, p'-dihydroxydiphenyl 2 J/
jj Terephthalic acid / ! ,! 113
．． 3r biphenyldicarboxylic acid de4yp-
Hydroxybenzoic acid 710g iAcetic anhydride
g7j Ji' was charged, and the subsequent process was carried out in the same manner as in Example D. The melt viscosity of the obtained polymer was /100 poise, which was 1=72.3.

The total amounts of acetic anhydride and acetic acid at each time point of (1), (2), (2), and (2) were respectively 21% by weight, 0.93% by weight, 0076% by weight, and 00SS by weight.

Comparative Example 5 Polymerization was carried out using the same raw materials and amounts as in Example 5 and the same process as in Comparative Example.

The melt viscosity of the obtained polymer was 6.20 poise,
L=3t,2.

The total amount of acetic anhydride and acetic acid at each point of ■, ■, ■, ■ is 76.3% by weight, g, 2% by weight, g, 3% by weight, respectively.
, the weight was 1g.

Example 6 p-hydroxybenzoic acid 7 j-
0j-g cohydroxy-6-carboquine naphthalene
lIa, s i Acetic anhydride g
The process after charging o and o g was carried out in the same manner as in Example 1. The melt viscosity of the obtained polymer was 1020 poise, and L=76.3.

The total amount of acetic anhydride and acetic acid at the time of ■ is θ0gO weight%
Met.

Comparative Example 6 Polymerization was carried out in the same process as in Comparative Example 6 using the same raw materials and amounts as in Example 6.

The melt viscosity of the obtained polymer was 900 voids, and L
, =lIO,2.

The total amount of acetic anhydride and acetic acid at the time of ■ is 9.7% by weight.
Met.

〔Effect of the invention〕

The polyester obtained by the production method of the present invention has a low degree of coloring and has a good appearance, and can be colored into a desired color by adding a coloring agent, etc., and can be suitably commercialized as a molding material, film, or fiber. It is. Moreover, the manufacturing method has all the industrial advantages that the raw material compounds are inexpensive and the polymerization rate is fast.

Claims (1)

[Claims] (1) (i) Using at least a diol represented by the following general formula (I) and a dicarboxylic acid represented by the following general formula (II), or (ii) using at least a hydroxycarboxylic acid represented by the following general formula (III). or (iii) using at least the above hydroxycarboxylic acid and an oligoester or polyester having a structural unit represented by the following general formula (IV), acetylation with acetic anhydride in the system, followed by melt polymerization. 240℃ in producing polyester by
A method for producing polyester, which comprises performing acetylation as follows, and then substantially distilling excess acetic anhydride and acetic acid out of the system at 240° C. or lower, followed by melt polymerization. HO-R^1-OH・・・・・・〔I〕 ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・〔II〕 ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・[III
] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[IV] (Here, R^1, R in formulas (I), (II), and (III)
^2 and R^3 are divalent aromatic hydrocarbon groups, R^1^
1-X-R^1^2 groups, (However, R^1^1 and R^1
^2 is a divalent aromatic hydrocarbon group, X is an oxygen atom,
Sulfur atom, sulfonyl group, carbonyl group, hydrocarbon group,
Indicates an ester group or a direct bond. ) (However, the hydrogen atom of the aromatic ring may be substituted with a halogen atom, hydrocarbon group, alkoxy group, phenoxy group, etc.)
, R^4 in the formula (IV) is a divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or/and a divalent alicyclic hydrocarbon group having 1 to 40 carbon atoms. Indicates a divalent aliphatic hydrocarbon group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl or alkoxy group having 1 to 4 carbon atoms), and R^ 5 is carbon number 2~
40 divalent aliphatic hydrocarbon groups, divalent alicyclic hydrocarbon groups having 4 to 20 carbon atoms, and 6 to 2 carbon atoms forming an aromatic ring.
0 divalent aromatic hydrocarbon group (however, the hydrogen atom of the aromatic ring of the aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group),
Or it represents a polyalkylene oxide divalent radical having a molecular weight of 80 to 8,000. )